Is it OK to have multiple different rooms on one breaker?
You can logically have many rooms on one breaker.  It is really about what size the breaker/wire is and what it will be powering.

Given that you have a kitchen (usually 2-3 breakers minimum) and 2 bathrooms (usually on their own) plus extra I would tend to say that you have too much on it.  I doubt it would pass any current inspection.  

Would I be concerned as far as safety?  Maybe.  If you are using too much your breaker should flip.  However when things are maxed out over long periods of time there are usually degradation points.  I would personally have it looked at by local inspector then  electrician.

This is really an over simplified answer but I hope it gets the point across.  What you are describing isn't normal by current standards and should be looked at.  If you give us more exacts - number of lights and outlets and breaker/wire size we can provide more science around it.