Family politics... how to handle the in-laws?

My boyfriend's sister had her baby about 5 months before Dominic was born.  At first I thought how great to have someone that's been through this right before me so I can go to her with questions, get advice from, etc. I quickly realized that this wasn't a blessing. It was more a complication of how to deal with the in-laws when we choose different ways of raising our babies. That I will forever be compared to how she did things and have to rationalize my choices and argue with them when I want to do things differently. This became obvious to me even before Dominic was born. I knew even then that I would forever be known as the bitchy controlling mother to my boyfriend's side of the family. And of course this has come true and I'm learning to live with it, though it definitely has caused problems with my boyfriend and I.

The first moment I realized this was to be my fate was when every time Dave's nephew made a sound, he was given a bottle. He must have be hungry they claimed. Even Dave's sister had said that the doctor had told them to stop giving him so much formula, but Dave's mother of course ignored that and still was giving him about twice as much as was recommended.

The second time I became concerned about how I was going to deal with his family was when Dave's sister and mother came over to visit with the baby. They were nice enough to bring us some ice cream. It was a beautiful night and we were sitting in my backyard, then to my shock, they were dipping their fingers in the ice cream and giving it to the baby who was 3 months old. I'm fully against stepping in and saying anything about her choices and giving advice on raising a baby, I was after all still just pregnant and haven't even been there. But I did mention I thought that you weren't supposed to give sugar to babies until at least a year (this is how we've always done it in my family - the first sugar is giving on the first birthday). She said well there's sugar in formula, and she's been giving him some juices from fruits and that already. I dropped it. I didn't want to get involved. I was sure all babies needed until 6 months were formula or breastmilk, in some cases you can start introducing some things early. After they had left, I told Dave that we're not going to be giving Dominic sugar for at least his first year, which caused a fight. Dave has a need to protect his family and thinks that everything they do is right. He said they're not doing anything wrong and a little bit is okay. I said its not about right or wrong, but we're not going to be doing that with our son.

By 5 months, Dave's mother was literally spoon feeding the his nephew ice cream, giving him icing from a cake, and almost gave him gingerale. I couldn't even watch when they were giving him the ice cream. Dave even made a comment that it was too much. Again, I'm not one to comment on what's right or wrong, but I still couldn't believe it. I may be overly cautious and read too many books and articles, but I know I don't want that being given to my son.

When Dominic was first born dealing with Dave and his mother was a total nightmare, and made having a new baby even more stressful. We were having trouble breastfeeding the first couple of days because my son was a sleepy baby and would fall asleep (at the time I didn't know that I was supposed to keep waking him up). Dave and his mother told me I was starving the baby, that he's hungry, that he's too small and losing weight (he did lose weight the first day, and after that wasn't gaining weight very quickly, but after 5 days we went to a lactation consultant and to make sure he was gaining weight), and his mother even told me that her 4 kids never cried, and clearly I'm doing something wrong.  All I could do was cry. Luckily I had my mother, and my cousin to support me and we managed to tough it out. We listened to the doctors and the lactation consultant and kept going. For the first month my boyfriend still would tell me every time the baby made a noise that my boobs weren't working and he's not eating enough and we should formula feed. But I resisted and listened to the doctors - who were very happy with his progress. Finally Dave stopped and gave in that that breastfeeding was in fact working. Every now and then he says he wants to formula feed, but he's realized I'm not giving up on it. So for now I'm safe... they seem to butt out and leave me alone to feed the baby now and Dominic is 3 months old. But I'm terrified of what's going to happen when I do start introducing other foods - are they going to think they have a free pass to give him whatever they want without clearing it with me? Are they going to overfeed him every time he makes a sound (his mother still every time he's awake says he's fussy and must be hungry)? How do I explain why I don't trust them alone with my baby without causing them to be upset or my boyfriend to get angry at me? I think the worst is yet to come when dealing with my in-laws... and my boyfriend for that matter.