Is self-love a sin after all?

I'm very confused lately. I am christian, I do believe in God but I have moments when I'm in doubt. Nowadays everyone promotes self-love and how we shouldn't settle for relationships with people that are so called toxic.

But the Bible says that we shouldn't be arrogant , or say good things about ourselves and that we should care for others more. I'm confused, am I supposed to make myself unhappy in order to care someone else? Am I supposed to not care myself?

Does it mean that if I put myself first I'm doing against what Bible say?

I'm definitely not happy since I stopped to put myself first, I settled for less and even start to think that it's ok to be treated bad.

I wasn't thinking this way before, but lately i started to see that from this self love that social media promotes and having a big ego is a fine line. I don't know anymore what is good.

Is self-love a sin after all?
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