When I was a teenager I hung around a recording studio and got chatting to the owner many times. His advice was this....
If you think your music is crap everyone else will think it's the most awful thing they've ever heard.
If you think your music is good everyone else will think it's crap.
If you think your music excellent everyone else will think it's good.
If you think your music is the work of genius everyone else will think it's excellent.
I try to be my worst critic. That said it's also healthy to evaluate your own work by comparing it to your peers and influences.
At this point in my career I can confidently say I'm rather good at what I do. BUT, I still have a lot to learn.
Never knock yourself too much but beware your ego too.