You have time to change your story. 28 is not that old. I didn't meet my husband until I was 34; my sister not until she was 39.
Live your life for you, be your best self, forget about looking for relationships. When you live for yourself and engage in the world the connections you make are your best chance at finding the right person. Without actually looking.
You did write two things that I think you should work on, however.
1. "I did everything to be as perfect as possible."
Relationships aren't about being perfect, they are about connecting. While, sure, people try to be their best and most attractive foot forward while dating, long run if you aren't revealing the real you, and connecting as the real you, you aren't having a relationship. You can't live your life as anyone but yourself, and neither can she. You have to slowly reveal your flaws and baggage and be vulnerable to each other. You can't have a relationship otherwise. All you can have is some mild casual dating. Basically, doing everything to be as perfect as possible is going to be self-defeating, because it gets in the way of making any actual real connection.
2. "I didn’t push your boundaries because I did not want her to break up with me."
In order for a relationship to progress, you HAVE to take risks. You have to be vulnerable. If you live in fear of her breaking up with you, you aren't in a relationship. There is no two way street. You can't have a relationship without a two way street. If you don't learn to take the risk, you won't be able to sustain the perfect relationship when it comes your way.
Hopefully the right person will make you feel secure enough that you won't feel drawn to create these false barriers. But before that, you probably have to kiss a few metaphorical toads and fail a few times. It is very rare for someone's first relationship to also be their forever. Most of us need to experiment a bit, fail a few times, and test the waters with some of the wrong people before we are ready to truly be in a permanent relationship.
You are already ahead of the game compared to many people because you did get a girlfriend! A one year relationship is a super solid start. Learn from it, and don't be afraid to try again. It's what we all have to go through, regardless of our neurology, and regardless of how many "nos" come before the next "yes."
It hurts now. Let yourself go through that. I don't want to mitigate how much it can hurt when a relationship ends. You have a right to feel it and express it. But, eventually, you can and will move on.
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).