i never used formula, but when my first was one I went back to work, so he did have whole milk at the day home, and BF when with me. He weaned at 20 months, I was 4 months pregnant at the time. My milk supply dropped a lot when I got pregnant and BF became increasinglky painful. I was ready for him to quit as I could hardly stand the pain! With my scond, I plan to start whole milk agian at age one, and BF when I am not at work, and I will encourage him to wean at age 2 if he doesn't on his own by then. I'm interested in going much past age 2.
There is absolutly no problem to BF while pregnant. The only time it is not advised is for people who have a serious risk of preterm labor, and that is quite rare. There is no problem to BF if you are small. Your body will just encourage you to eat more, because you will need lots of nutrients, so expect to be hungry. The milk will still be nutritious and the unborn baby will grow.
The only people who gave me any grief over BF past a year where my husband, he was fine with it as long as no one saw, and was disturbed if I BF the toddler in a restaurant, but although very annoying to me, I didn't let his attitude stop me. My grandma was horrified, and I know my mom thought it strange too, although she only made indirect comments to it. I recognize that they are only uncomfortable because they are not used to it, if more people BF toddlers in public, then people would be used to it and not think it strange.