Help me build my self esteem and confidence

hello my names Katie I am 34 years old, I have four beautiful children. I have very low self esteem and no confidence since breastfeeding my children I lost all my breast tissue and I am now flat chested, i have had nasty comments said to me and it's got me down. I had no confidence and made my relationship break down. I just wanna be happy with my appearance again and be able to take my kids swimming and things like that.