This is a hard feeling to get over, but trust me, eventually you will and must. We look to our parents for everything for so long, it just becomes natural to feel that way.

Be confident in yourself and do whats right for you first, and whats right for everyone else second.

I second the idea of keeping the carb counting et al to your self. Its hard for a mom to argue with meat and veggies. Another suggestion would be to ease into it. Start by cutting out junk foods like pizza, chips and fries. No one can argue that is unhealthful. Then slowly move onto the more 'normal' foods like bread. You mom might not even really pay attention to that.

Good luck low carbing, you will feel great!