I suffer with low self-esteem as well, so I know how many problems it can cause for you. My therapist recently spent time with me trying to find the beliefs I have about myself, for example I can't do a lot of things because I think people always judge me negatively (because I see myself in a negative way). By taking small steps to do the things I find difficult, such as going somewhere I have to interact with people, I am slowly learning that people don't judge me as much as I think they do.
So maybe you could write down the opinions you have of yourself, and then set yourself small goals to overcome them. I've no idea if this makes sense, I'm not good at explaining myself.
Another thing you can try is to write a positive description of yourself. Or maybe ask other people to?
Good luck