How many cm before theyll keep you?

How many cm dialated do you have to be before they will keep you at the hospital? at my doctor appointment thursday i wasnt dialated and 2 days later at the hospital i was 2cm. ive been having contractions on and off since then and alot of pressure in my lower belly so my guess would be ive progressed from 2cm to some point. i have another doctors appointment in the morning and im just trying to get a ballpark idea of how much i wouldve had to progress in order for them to keep me tomorrow. my bags are packed and ready to go, im just tryin to see how likely(or not) it could be that ill be in the hospital this time tomorrow night.