My ex told me that I had to stop medication because she said she viewed it similar to being an alcoholic. She knew my mom was an alcoholic and she knew my hatred for alcohol would make me stop taking the medication.

You shouldn't be taking medical advice from your girlfriend, right? In fact, you should pretty quickly point that out to her and tell her to stay the hell out of it.

I stopped taking the medication because I didn't want to be compared to an alcoholic.

Sounds like she manipulated you quite a bit.

I was diagnosed with Autism Spectrum Disorder

Cheers for opening up to me dude.

I feel like I can't seem to find any girl who truly cares about me.

It's much easier to get into a relationship with a broken girl than a healthy one. Healthy girls expect healthy boyfriends. The further you are from the top of your game, the less likely you are to attract a good caring girl.

What you said in your original post about how you're looking after yourself more now, working out and going out and things, that's the key mate. Those things make you a better you, those things will enable you to attract higher quality girls.

I fear that if I don't act now, then I won't be able to connect with anyone ever again.

Absolutely get out there, live your life, meet people, have experiences, flirt, date, etc. Just don't rush into the "head over heals over this girl. I would do everything and anything for her" thing too soon, or ever again. You have to play things a little bit cooler even if that's how you feel. You should consider your time and effort to be valuable things and expect them to be respected, they're not to be taken for granted. Don't play games, but don't take shit either.

every relationship I've been in has resulted me in attracting girls who don't give me a reciprocal relationship

This is either because you're coming on too strong and suffocating them, or you're bad at detecting users. I think that's the biggest thing you should be mindful of.