I agree. I have had to listen to the same things. Not so much with breastfeeding but definitely with using cloth nappies. I have had to listen to ppl say "Oh that won't last, I give you 3 months then you will switch to disposables" and "why give yourself extra work, don't bother just use disposables" etc etc.
I guess the criticism starts in pregnancy, the only thing we can do is stick at it and prove them wrong, that should shut them up. A good friend of mine told me that usually pp who make these comments feel as though you are having a dig at them. Especially if they have had children and used disposables or bottle fed, they feel as though it is a personal attack on them b/c your not doing the same and that you are basically saying they are a bad person for using disposables or bottle feeding (which we are not - it's just personal choice).
Stick to your guns hun and when they see you are doing what you want, hopefully they will leave you alone. Try not to let it get to you.

Enjoy the rest of your pregnancy.

All the best!