please, how do i fix low self esteem?

having an epiphany i am my biggest critic and it's killing me that i can't even accept compliments, my immediate reaction is to deny and move on

You're not alone! 

Not sure if this is a contrarian take but I think it's functionally impossible to will yourself into improving self-esteem. Instead it comes from building proof/evidence of things you're proud of yourself for over time, acknowledging those wins and the momentum that comes from that

building my web apps give me confidence, same with working out, but when job applications start to ask for my skills & experience can't list one thing

If you feel like you don't have any marketable skills/experience, then the focus should be on building those (which it seems like thats exactly what you're doing!)

It's def frustrating experiencing the gap between where you are and where you want to be but at end of the day you can only focus on what's in your control