I don't trust my own judgement, have low self esteem and tend to wish I'd made other choices in hindsight. At the time I tend to always go for the option that is least hurtful to the other person regardless of myself.
This stood out for me, as you are being very hard on yourself. I wondered whether you recognise that in yourself.
I'm sorry that you see it as a settled fact that you have low self esteem, rather than something you have noticed about yourself that you are thinking about how to change.
Self esteem is a hot topic, with lots being written about it.
The key thing for me is that we often think ' I have low self esteem so ... I do ...' whereas in fact the reason for the low self esteem is literally how we treat ourselves. Always putting yourself and your own needs last is pretty much the definition of low self esteem.
It's a really common feeling. We are often rewarded for being 'selfless' and generous to others. Good in its way but in real life we need a balance.
Sorry if this sounds off topic and not well explained. I'd encourage you to think about how you would treat a friend, as sister or a daughter ... and then do that for yourself. If you treat yourself at least as well as you would treat someone else, and do it as a matter of what is owed to you as a human being, you will be building up the 'muscle' of your self esteem.
Do that each time you have a decision to make. Don't expect that you will always make the right decision. Be gentle with yourself when you find that things didn't turn out as you expected or even hoped. You can know the future. You can only make the best decision you can at the time.
Find the courage to be kind to yourself. You deserve it. All the best.