Hannah, yes you are young and probably still in the 15yr old mind frame as though you haven't grown as a person since you met the older man, got pregnant, and gave your baby up. You then jumped into another relationship. You have a lot to look at but you are not crazy, just a bit lost. I think once you start to learn about yourself and meet people with issues just like you you will open up a whole new world of friends and support you never knew was out there. You will also find that you aren't so unusual. Many people your age have your story or a similar one - YOU ARE NOT ALONE! As for what other people think? You can bet most of the time other people only think about themselves and the ones that judge don't need to be around you.
There are so many options for you so don't get yourself all freaked out about in patient. you may be okay with out patient or NA Meetings and a therapist to begin with. Bottom line is you can't do this alone. Also when you are as young as you are and in a relationship the other person in the relationship isn't mentally equipt to handle addiction and this may be what you are seeing in your boyfriend. Why do you have to be in a relationship? Have you spent much time on your own?
Whatever the issues you have to get help and I'm really glad you called.
Don't worry you will be okay. Slow down and let those that know what they are doing help you. Accept the help, respect it and listen to those who "have been there." You will find your way. ((HUGS))