The game autosaves on every room for convenience but safe rooms should save in a separated slot. There was one right before the entrance of the Gardens, two screens from where you are now.
To be honest, i think it's possible to ignore every save prompt in the safe rooms but it's highly unlikely. Is this the case? The auto save always saves on slot 8 while the player chooses the specific slot for the main one.
Aside that, it's fairly common to get locked in an autosave since the game was designed around resources management. At first, it wouldn't offer auto saves at all, but i thought it could be a nice quality of life feature. Though it can be misleading at times.
Can you load a main save from the last safe room?