Yellow toenails

My big toenails have been yellow for years now, probably over a decade. I was a kid when it first started, I didn't think anything over it. Then my teens hit and I got embarrassed about it. I've been wearing nail polish for years now. When the paint starts to chip, I'll either add another coat, or use remover to get the rest off and immediately put more on them.

I've never seen a doctor about it because it's embarrassing now. I know I should go and that they're there to treat me but the fact that it's been so long makes it hard.

Does anyone know what this might be or have any recommendations for how to treat it?