I shared a bedroom from the day I was born until I left home aged 16, but it varied who I was sharing with.
I always shared with my twin sister and we get on really well and always have. We talk about anything and everything and we help each other out and whatever. The fewest people that I've shared a room with was 2 others when we were really little, so there were 3 of us in there altogether. The most total people sharing my bedroom was 7, including myself. That was from when I was 14 until I left.
I don't really see a need to have my own bedroom. Solo bedrooms get really lonely and you've got no-one to talk to or say goodnight to. I don't care about my siblings seeing me change because a body's a body and mine's nothing special. Also, because I'm a wheelchair user, when I was younger I used to have to get my older siblings to help me get changed, so I was always used to them seeing me. Also, my big sister used to have to watch me in the bath in case I fell over or had a seizure. That was right up until I left, so I just didn't have time for body issues.
The only bad part of sharing was having limited space to put your stuff, especially when there was 7 in a room. Our wardrobe space was certainly limited.