Wrong race that would upset my parents

Your parents aren't going to date your partner, so their opinions on her race mean absolutely nothing. It's like going to a restaurant with a friend and they tell you you can't order salmon because they don't like it. It's not their food, so what they say doesn't matter since they're not eating it.

Feeling that my interest in the other person is not genuine and that I only see her as a sexual object

This felt a little too real to read. I know that feeling, and it's not nice. I got no advice here, just letting you know you're not alone in feeling it.

I have this dreadful feeling that I missed out on something important in life

The best part about life is that you get to define what's important to you. Some people may find meaning in having a family, but it's not the only objective way of finding meaning/purpose. You could find joy in creating things, exploring the world, even just working. There's no secret formula or shortcut to finding it, and there's definitely no hard rules about what it can be. I hope this helps you feel better.