M.D.
It sounds like you don't actually want to wean him, you are just concerned about this upcoming trip. If you don't want to wean him, don't! Just pump to maintain your milk supply and prevent engorgement while on the trip. You can either save the milk or just pump and dump. When you get back, resume life as normal.
It sounds to me like your doctor does not approve of the parenting choices you have made concerning co-sleeping and breastfeeding. For that reason, I would take all of her advice with a grain of salt, because she may have an ulterior motive.
I was recently hospitalized to have my appendix out, and because of some medicines and chemicals in my body, I was unable to breastfeed my son for 3 days (he is 18 months old). It was unplanned, so there was no way to prepare my son, and no way was I going to wean him cold turkey just because I was unable to nurse for 3 days. He ended up being fine, his father took care of him and he did go to sleep in our bed with his father in my absence (we co-sleep as well).
I think you may be stressing yourself unnecessarily. I thought the same thing, that my son would be unable to function while I was in the hospital and recovering, but he was fine. I was proud that he was able to bounce back so well from a big disturbance in his routine. Im sure your son will be fine too.