When will I be comfortable sleeping on my side after bilateral mastectomy with expander?

I had bilateral mastectomy with TE August 2016. Expanders replaced with implants 2 weeks ago. When I sleep on my back or side it feels like the muscles and implants are pulling down. When I get up I feel like I have to hold my breasts close for support. I only feel comfortable when I sleep in the recliner with the arms supporting me. I still feel like I have an iron bra on. Is this part of the healing process and, How long before it gets better? Will the filling of having a bra on go away?