What does it mean to believe in yourself

I have a question. How do you end up believing in yourself, because I’ve done something I used to believe was impossible when I was little and I even believe it to be my biggest accomplishment. It was beating 50/20 in Fnaf ucn, it was a dream come true. It took me 108 hours. After I did it I thought to myself “if I could do that than I could do anything” but I’ve started to kinda just toss that thought away. Even though I’ve succeeded my accomplishment of beating 50/20 by beat Nocturnal Nightmares: Nyctiphobia, a harder Fnaf max mode, I still can’t help but think that I can’t do anything good irl. How do I take my determination and grit out into the real world

I also have trouble believing I’ll ever be feminine. I want to transition but honestly I don’t think I can due to family and self doubt in my looks and so much more

Bwah