Sometimes people don't know what to say. It is better than 'you've got such a pretty face', isn't it? I hate that. Soon I will be asking, do you know any good places to donate all these clothes that are too big now?
Do it for yourself and tell yourself how hard you have worked. YOU know you look great and they do, too. Even if they don't say it!
I am sorry for your struggle. The answer is that being able to conceive and give birth is no guarantee of parenting skills...and neither is the inability to do the same an indication of being a poor parent. Every child deserves the best, sadly some don't get it.