First, you should try to compare yourself less to your peers. Everyone has a different path in life, and you might be selling yourself short. Some related reading for you!

Second, since I find myself struggling with the same thing; I try to find something to engross myself in that's unique from my peers, since it can give me a sense of accomplishment by allowing myself to look forward to my own goals, rather than sideways at what others are doing. I dabble in a lot of things, but am usually not an expert at many things I've done--I posted in this thread about building an R/C Quadcopter with a friend, which will be a cool project, but I've also learned the basics of knitting and rock climbing over the years just because of personal interest. I'm not particularly good at either of these things, but it was still cool to learn!

You probably already do this, though. I know you run a gaming blog and have done LP's with your sister, and I think that's awesome, but the bottom line is that you need to start counting your worth in terms of what you can do, not what you can't. (Idk if I'm being too presumptuous with this advice, sorry if I come off that way!)