Hello KindEyes and welcome. I like your name. My husband Still Totally ADD told me about your post and suggested I share my thoughts with you. Like you I am a very introverted person. Still Totally ADD and I are in our sixties now and have been in the cult most of our lives, he a born-in, me a convert. Though I hated it I learned to be more outgoing by going in field service and giving regular talks on the ministry school. So when I left the cult at least I could approach people. My husband though is the outgoing one and I rely on him a great deal to take the first step to forming friendships. You say you have an amazing boyfriend. I'm sure you will find him a great source of support.
Look around at work and at school. Is there anyone you would like to get to know better? Say "hello", give a sincere compliment, ask a question, show interest in the person. Pretty soon you will have a conversation going. Don't be afraid of your JW past. I find many people are intrigued by someone who lived through an unusual experience. Know that not everyone is going to be your friend. You are free to choose who you are comfortable with. Most of all be sincere and be true to yourself.
As for your toxic JW girlfriends, surely you can see they are using you. You don't need them in your life.
Best of luck on your journey into the real world.