Dear sister, Ma'ashallah, I'm sure Allah's so proud of you, Allahu Akbar.
Inshallah sister, you see as muslims, we can only do things which the Prophet Muhammed s.a.w or Allah have imposed on us, everything else that we add to the religion is bida and innovation, and hence, very much hated by Allah.
There is no hadith or Ayah of the quran which says a party has to be thrown.
You may do so if you wish, just to get the sisters together, but not as a means of an imposed obligation from Quran or Sunnah.
Remember, all that is good for us and to our benefit, Allah has told the prophet s.a.w, he has not forgotten anything (astagfirullah):
"I warn you of the newly invented matters (in the religion),and every newly invented matter is an innovation, and every innovation is misguidance, and every misguidance is in the Hellfire" (an-Nasaa'ee)
whosoever introduces into this religion of ours that which is not part of it then it must be rejected" (Ahmad)
"whosoever does an action which we have not commanded then it must be rejected." (Muslim)
"this day have I perfected your religion for you, completed my favour upon you, and have chosen for you Islaam as your religion"
(Surah Al-Ma'idah 5:4)
"and We have revealed to you a Book explaining everything"
(Surah An-Nahl 16:89),
and He says,
"We have neglected nothing in the Book"
(Surah Al-An'am 6:37).
"indeed you have in the Messenger of Allaah an excellent example for the one who hopes in Allaah and looks to the Last Day."
(Surah Al-Ahzab 33:21),
"so if you obey him (i.e. Muhammad), then you will be guided"
(Surah Al-Furqan 25:54)
I have left behind me two things, if you cling to them you will never go astray. They are the Book of Allaah and my Sunnah" (al-Haakim)
"or do they have partners that legislate some religion which Allaah has not given permission for?"
(Surah Ash-Shura 42:21)
Abdullaah ibn Umar (RA) states, "every innovation is misguidance, even if the people regard it as good." (ad-Daarimee)
Inshallah, I hope this helps sister. May Allah bless you for wearing the hijab and bless you with all your heart desires.
Fatima.