Hello Snowrt! Welcome to PC!
First, I want to rephrase something that Lee said. I know she meant it with the best of intentions, but I want to make it clear that all types of men like all types of women! No two people have the EXACT same preferences regarding what they want in a mate.
I agree that your mother shouldn't have said all those things to you, but she was projecting her own issues on to you, and maybe even felt like she was protecting you. It is possible to be a good mother with her own baggage that simple gets in the way. From now on, if she says something like that to you or one of those times comes to your mind, replace the "You" in the sentence with an "I." Meaning, when she says "You won't have any fun dress shopping," try to hear her saying "I won't have fun dress shopping." I know it's impossible to unhear everything your mother ever said to you, but now is the time to acknowledge it for what it was and move on. I know that is way easier said that done, but, in DBT, they teach what they call "Teflon Mind" (I'm sure the teflon people love it), when you acknowledge it for what it is, then try to let it go.
In regards to your high school friend, I feel that you should try to return to being friends with him. Don't chain yourself to him or pine away after him, but I wouldn't actively pursue him while he has a girlfriend. If you're truly interested in him, try to rebuild your friendship with him. Staying a part of his life, returning to what you once had, might give him hope again. I agree with Lee that if someone asks you if you have feelings for him, don't say no. But I wouldn't tell him directly unless he comes to you and asks you himself. Try not to cause trouble for him and his girlfriend. He has to make up his own mind, and that's always easier when their isn't drama going on.
You are a good, wonderful, loving person. I agree that seeing a therapist might help you build up your self esteem and self worth, plus wade through all the baggage from your mother. I truly believe you will find someone that loves you and wants to be with you and values your presence in their life. Don't give up hope on this. Work to get yourself to a stable and self-loving place.
Good luck!