I have just now come to this thread, and I applaud your courage. it is a huge challenge to re-think your life, and come to realize that some things whih you have held to be true about yourself, were not. This is a major step for you, and in my humble opinion you should start with small steps. I think Aish HaTorah Discovery seminars would be of tremendous benefit. Or Rebbetzin Esther Jungries’ Hineni (meaning “here I am”)organization. They are geared to educating and welcoming the Baal Teshuvah.
If I understood your post correctly, you ARE Jewish by birth, as it is passed down matrilineally. If your mother, grandmother and great-grandmother were all unquestionably Jewish, then you are, too (really it only needs to be that you look at your own mother being a bona fide Jew (whether by birth or Orthodox conversion), but it is a good idea to check back further down her maternal bloodline).
Much good luck to you in your endeavors to live a life that is your heritage. It is well worth it. Find yourself an Orthodox rabbi and his wife, with whom you can make a real connection, and try to spend your Shabboses in their community. Why travel on Shabbos, if you already are making inroads to committing to a true Torah life?