Sister, let me tell you something.
I was born without a father (died in war before i was born), at the age 9 i went to a western country living with my uncle, leaving behind my mother, brother and sister. After 5 years, because of abuse from my aunt, i run away and i became part of those temporary places that kids are taken in. Between the ages 14 to 18 i had moved 8 times from one place to another. At the age 18 i finally went to a place and i stayed there finally to have stable place so to say. My own family that i had in the western country that i lived, nobody cared about me..everybody busy with their own stuff. My two friends never from a young age till even as a adult never knew me or what i experienced or what was going through my head. Loneliness is something that hits you hard, but i do not regret that life even one bit. That live thought me what really is important. It also thought me to be critical and take wise decisions. One of the MOST valuable things that i have learned through out the years, do NOT depend on people. Being help with something or having "fun". Many times sadly people expect one way or the other that you help them with something, that you might for example reject as it might not go with your way of life or mentality. I have sub'han'Allah till this day even got wisdom of what i have experienced back then. I do not feel sad, rather i feel joyful because experiencing those things and realizing that i have could gone astray so much becoming a criminal..killing somebody, dealing drugs or using drugs becoming a alcoholic, or a player, or gambler or whatever. However sub'han'Allah even on my own through many of those years i somehow did not went one of those ways. Knowing this for example, you can only conclude that Allah(swt) was really with me through all those hardships, although i never though of Him, He never forgot me. While, people would already have dropped you without hesitation.
I have become Muslim again about 4 years ago after being an atheist for about 7 years and what i have seen is that people we THINK are our friends are the ones that LEAST understand us and what we are going through. Just because we one day had something in common, doesn't mean it will always stay like that. The two "friends" of mine, one married and the last 10 years as an atheist and also as a Muslim, he always had his "secret" agenda so to say. Only using people.
The other "friend" is the type that hears you talk, but never listens what you are trying to say. He wants things to be as things "were"...but he also does not believe in change. Not to forget, he still sees me as the person i was 12 years ago..all lost and my mentality back then of having hatred inside me. He tries to push his values of what he finds important that i also should find those things important. Sadly this friend of mine he was 12 years ago a very optimistic person compared to me back then, while now the most cynical person to hang out with as things haven't gone as he wanted go and expected things to go. All he cares is his goals and i have tried to tell him to be critical of his goals as they might not bring him the happiness that he is sort of searching for. He really cares about what other people think of him and see him. For him this whole life is a competition to with achieving worldly things. You know that type of people that buy something and one could say they have ONLY bought it to show it to other people..look what i have bought it..mine is better than yours. ....I AM better than you..mentality. These cynical people, will not listen to what you have to say. You can do little to help these people as they want you for example to do things, like couple of months a go we went with the car to another city and out of nowhere he wanted to do haram things =_=!. Off course i objected it and later on he said that he does not plan things but acts on impulse. These people CAN NEVER become your friends as long as they are not Muslims. As friends will help each other through everything and join them with all kind of things, but Muslims have their boundaries that they cannot cross.
I for bigger part keep myself busy as i myself also do not have "friends" so to say. The Muslims at the mosque are one way or the other kind of extreme in their mentality now a days because of what all is happening to the Muslims. In these times to have good friends is a rare thing. These same people that are extreme in their deen, will drop also in extreme lows when their imaan is low. In other words, taking you with them in their drop. So my advice to that, be very careful. Rather being alone with Allah, than being surrounded by people who do not thinking of Allah.
Keep yourself busy with reading beneficial things, watching beneficial videos. Having even maybe discussions online such as this forum. Often is our mind that feels this loneliness, while for example being on the internet, the mind is suddenly free and not experiencing this loneliness you are talking about. Have a hobby or two as there are A LOT of things to keep your self busy while they also are beneficial to do. When you feel that you are a stranger among people with different mentality now a days, know that you are somehow on the right path. We will experience hardship through all means. As many of us will experience loneliness but our soul can take it, or else Allah(swt) would not put us in these situations.
Be aware to reach such a stage is NOT easy at all, if you your whole life have experienced social mixing all the time. So switching from one thing to another is seriously hard. Keep in mind to not go all haywire as some people lose it, because of loneliness. Many people think a lot and because of that, lose for example their social interaction. As not being able to socially interact with people if they are in such a situation. However, that you have become Muslim, says a lot about you. That you maybe yourself aren't that type of person that likes to be surrounded by people 24/7. As those people that are surrounded by people 24/7 and like to be surrounded by people 24/7 will be the last people that will ponder about life or search for the truth. They find this 24/7 mixing already the truth and no reason to look further.
So do not be depressed and when you are feeling it, go and pray. As often it is lack of not being able to talk to somebody, so go and talk to Allah(swt). As He hears us and always hears us.
Also if you need to talk to somebody..a real person, i am sure there are some sisters who want to talk.
Peace and take care