K.C.
You are NOT taking away from your baby!!! Your body takes care of the unborn child FIRST. I just went through this and can honestly say there is nothing wrong still nursing. Everyone looses their milk at different times in pregnancy and some not at all. I lost my milk at 20 weeks and my son was completely ready to stop at that point, it became more frusterating for him to try to nurse than not nursing. We had a water bottle by the bed (our bed) and stopped the middle of the night nursings and replaced them with the sippy filled with water every time he woke up. He knew where the sippy was and could get up and get it. I was too tired to nurse him in the middle of the night as you are saying, in the first trimester. It took about 3 nights, I held him and cuddled and he cried but I told him that the milk was all gone at night but he could have some in the morning. Instead, he could have the water if he was thirsty. Then, as I said, by 20 weeks pregnant, I was just out of milk and there was no problem stopping the morning/night feeding becasue he was frusterated with the anticipation of not getting anything.
As far as sleeping, I would say don't do it all at once. Either stop the nursing in the middle of the night first, or put him in his own bed, not both at once. We actually put a twin mattress on the floor of our room and had him there for a while. He knew he could crawl into our bed, but he started out there. I would nurse him in our bed then when he fell asleep, I moved him to his mattress. He ended up waking up and asking me to come lie on his bed instead of him coming into ours. Then, a couple of months before I had the baby, we moved the mattress into his room, made a big deal out of it, and he started sleeping in there. For a couple of nights, I slept down there with him because I fell asleep while he was trying to go to bed and for a transition. It worked out very smoothly.
I do have to add the warning though: when the baby came home, my 2 year old wanted only me to put him to bed and he was waking up a lot again. For the first month she was here, the three of us slept in Evan's room (Evan, myself and the baby). Now, 2.5 months after she was born, Evan is sleeping through the night and the baby and I are back with my husband and she is actually sleeping in the bassinette because she does not like to be touched while she is sleeping, so every child is different, be ready for a twist like that!
Good luck with your pregnancy and I hope my experiences help you!