You may have a negative outlook about yourself but that doesn't make you a bad person.
Your worst critic is probably yourself since you can judge every single thing you do.
The advice I'll give is to always look for the silver linings. You can't say you're a
complete mess without any ups, that's statistically impossible. You can think, therefore
you can understand what you do. You may not understand your reasoning afterwards but at
that moment you had a clear reason. Even if the reason is based off of an outside source,
your own mind thought about whether it made sense to do. If you're going to take anything away
from this it should be that you don't have to love yourself to be a better person, just
have the drive to improve yourself into somebody that you'll be contempt with being.
I mean, you definitely have thought, "Why did I do that? I should have done this!" You are
recognizing how to better yourself, just don't let that feeling linger and use it to push
yourself forward.
It's fine to be critical towards yourself. Just make sure you recognize that you absolutely
have excellent traits.