Ok Im going to try explain this very easly..

Me and my girlfriend have been going out for 9 months now I bought her a promise ring at 6 months. It all seemd very fine until a few days when she told me she doesn't know what she wants, doesn't very as attracted to me, doesn't know if she wants a serious relationship, needs time to think about it cause she doesn't want to make the wrong decision of breaking up or staying with me. This was a long distance relationship we seen each other every week and sometimkes every second week. We planned on moving in together in 2 months but I fear she will break up with me before then and yeah.. She also told me we don't have much in common which I strongly disagree. If you asked her family they say we are perfect for each other. Uhm, When I get drunk and stuff recently past 3 months I been acting like an idiot around her for some reason and depressed, mainly because I reallyloved her and just was pissed that she had to go or I had to go. But I quit drinking 3 weeks ago and sober since and true to my word. I did it for our relationship. But she told me this now a few days ago and its really hard. She also said that she feels like a serious relationship is holding her back that is 100% untrue unless she's talking about the partying/jing anyone. I really think she's the one and I thought we were perfect but obviously I was wrong. Past couple weeks she has seemd very distant and just not as in love with me or something.. Her family loves me I mean they gave me 5 grand to invest in stocks and stuff. Of course me and her argue but who doesn't. She asked for space and right now I ant really in contact unless she calls me. But since she said that, it doesn't seem like she cares anymore.. is there anything I can do to save this, I really love her a lot and she means the world. But I think I already lost her.

I forgot to add. She also was said something like " Im not breaking up with you im just not sure and I need to think about it and see if im making the right choice" or something like "im not breaking up with you yet , I havnt decided yet" something like that

I recently went through with the same situation with my ex my advice is give her her space she wants if she comes back it was meant to be if not then that's the case and you'll have to deal wit it then it hurts I no
I did the opposite to what everyone was telling me and tried to keep calling and in contact with her which eventually pushed her away. It was the worst feeling I've ever had and still hurts now I don't want anyone to go through that pain
Good luck I hope it all works out for you

A. You keep saying ''she said which is not true''
This projects YOUR beliefs and feelings onto her which is a passive aggressive control thing. It also, to her, makes it feel like you are invalidating her feelings and where she is in life.
She most likely is feeling that you are 'running' the relationship rather than getting in touch with her inner most feelings and desires
B. You said that it was after you gave her the pre engagement ring 'you started' drinking and whatever
So that is a red flag to a girl that you may have acted a certain way to get her and then once you felt comfortable having her the real self came out.
C. She also may have been caught up in the aspects of being in love and then sat down and had a serious talk with herself that she wants more to life than a boyfriend and may be afraid you will hold her back from pursuing her dreams even though it may not be intention on either one of your parts. I know every time I have a boyfriend I unintentionally give up a lot of my dreams and goals because guys tend to want you there for them and their life. Just the way it seems to work.

If you want to keep her you need to back off a little bit yet be there for her. Show more concern about her feeling and her goals. Prove your support and encouragement as well as being understanding of her feelings and desires.