Ines It is difficult to lie on your back.
It is directly painful to lie on your belly. If you put pillows, back aches in short time because is arched, and to lie on your side is not much better.
yes, i had all these problems in the first few weeks too, it's very difficult at first. personally, it helped me to put a slightly harder pillow under my breast and then i was able to sleep on my side. It also helps if you are a back sleeper to put a blanket on the bed but underneath you. In general, however, it is an individual thing and above all a matter of getting used to it (I hope you never have to get used to it)