When I went to a committee, I read up all about it and saw that I needed to be repentant. I needed to be sorry for everything I did.
There are online WT libraries and people can help you get a hold of the elder books. Look up exactly what you did and legally what they can get you on. And look up what they're looking for. This can result in disfellowshipping, reproof (public or private), or a warning. Breath, and do some research and find out exactly how what you did is viewed and what the elders are looking for in that circumstance to disfellowship you - or to not disfellowship you. From what I recall, it was being very sorry for what I'd done.
I hate to see you going through this. And all-of-a-sudden too. Your mind is totally on this, and you're thinking of options, but there's never time to think of everything in a panic.
Leaving the JWs or eventually being forced out may or may not happen. But buy yourself some time to think and plan and do it right.
My suggestion is to do and say what you need to so that you avoid disfellowshipping. That gives you breathing room to plan. Talk to your aunt and see if she's an option - or others. Plan a move out of your parent's house. Something you can do on your own, not where you're not being pushed out. Even if you're continuing as a JW, develop an independent life where you're not dependent on Witnesses emotionally or financially. Then, if they disfellowship you, you won't be damaged as badly.
When I finally left the JWs, I was never disfellowshipped or reproved. I may not have a good reputation for leaving (and probably not the best before that), but the JWs can still talk to me. That is what I'd like to see happen for you. That the door is still open for your family and friends to at least keep that connection, even if it can't be as close as it once was.
And when I left, I had been building up worldly friendships for years. At school. At work. So when it came time to leave, I wasn't jumping off a cliff into the unknown. I had a group of people and when I left and lost the JW people in my life, it wasn't devastating. I had better friends who didn't judge every action.
IMO, it's best to keep what you have now and then use your time to plan for the worst later.
About your case, you can ask others, but are you engaged? That might have a bearing. Of course when it's with a worldly person, it's frowned on. And may I say, IMO, 19 is WAY too young to be getting married. You've never been on your own. People don't know what arc their lives will take. You and your boyfriend may seem great right now. And the promise of sex and the instincts that pull you together often blind you to negatives. But, if you were to get married, 5 years from now after the first thrill of sex is over, you could be married to a guy who drives you nuts. For little things. Like does he put the seat down? How uptight is he about the house being super-clean (or the opposite super messy)? Does he shave and leave the sink full of whiskers? When he's not all enamored with you because he wants sex, how does he treat you? How does he feel about your career? Going to college? Working? If you have kids, does he expect you to quit your job? How often is he going to want to leave you to go out with his friends 5 years from now?
That's why I believe in having safe sex if you have that strong urge and desire. Get that out of the way and take the time to really get to know the guy without the sex blinding you. And wait until you know more about yourself and the direction you want to take before entangling yourself with somebody else before you know what path they're on.