I've been using a pressure cooker with a slightly rounded bottom for years. I know the pressure relief valve still works, as does the normal pressure valve. As long as the pressure relief plus is still good, I'd say keep using it.
But the kind of pressures involved, especially it being super-heated steam pressure, is nothing to mess around with. When in doubt, throw it out. Recycle the top and bottom separately so someone else doesn't think they made an awesome trash pick. Don't know about yours, but mine is aluminum and after seeing what sudden aluminum failure looks like with bicycles, cooking under pressure seems iffy use of alloy...
I know next to nothing. I am frequently wrong.