Darren,
There is a huge difference between telling your parents in your mid teens that you are joining a make-believe "religion" inspired by a movie franchise, and telling them at the step of adulthood that you are converting to God's true word. There should be a difference as well within your own mindset regarding the two. I think that it will not be hard to find ANYONE who would indeed find the mere concept of jediism to be a source of redicule, so I wouldn't take your father's reaction (albeit slightly annoying) to be personally dismissive of whatever it is that you do.
You need to be serious about yourself and your life for people to take you seriously, and if you are now seriously a muslim inside and out, completely convinced and understanding of the tenets of faith and the pillars of Islam, and understand its history and what is the obligation to God, and most importantly how fundamentally it is to you and your future, then you need to take it as such.
So the first thing you need to understand is that your parents will always be your parents and you will need to treat them kindly and with respect even if they don't reciprocate or even if they are non-muslim.
Second, you need to go ahead and sit them down, and like the mature dedicated adult you have become, inform them calmly of your conviction and conversion. Talk to them like you would as always and do not take on any personas or use words and vocabulary only other muslims understand, this will further alienate them and that is not what you would want. You want them to understand your decision, know about it, and that they will need to digest it and deal with it. Talk to them about how good it is, how it was misunderstood, how it is really the religion of God, what it asks you to do and expects of you as a person. They will have fears and misconceptions, and that is understandable and it is your job to calm their fears and correct their misconceptions the best you can. If you can do no better, then that is fine you are not required to do more than what you possibly are capable of. In the end whether or not they are ok with it is not your responsibility, what is your responsibility is that you do your best in telling them kindly and gently and to be understanding of their emotions that will probably fluctuate.
Third, know in your heart that not your parents and not anyone in your current life is ever able to make you do what you wouldn't want to do, so there is no need to ever panic about reactions and that someone might "force" you to convert out of Islam or anything like that. So based on that have faith and act upon it.
Take a few small steps and insha Allah everything will be ok.
God bless.