Hi S.,
Sounds like it's time for a regular bed for sure! For now, put her crib mattress on the floor and make it up like a bed. You might just have to be a really patient broken record for a while--if she gets out of bed, put her back in. If she gets out of bed, put her back in. If she gets out of bed, put her back in.
You can always do really short time-outs at this age too or take something valued away for a short period of time to underscore your point that when she's in bed, she's to stay there.
Don't worry--this will happen. Our son was sleeping in a big-boy bed at 22 months. It took less time than I thought it would for him to learn to stay in bed. (And like you, I did not sleep next to him).
Good luck!
:-) D.
P.S. If she gets out of bed, put her back in.
P.P.S. The baby-gate on the bedroom door is not a bad idea, either--we did that sometimes. Just make sure that there is nothing in her room that she could climb on and/or hurt herself with.