Two weeks is not a long time when she keeps outsmarting you, she really hasn't had to stay in her room. She's playing you, little ones are so much smarter than we give them credit for.
Get a new, higher gate, I stacked two on top of each other. It does work if they're properly installed. I then found a metal one with vertical slats that was taller than most, he couldn't climb it or hoist himself over it.
Get door knob covers, I had cheap ones that could snap apart, I taped the seams with packing tape, he couldn't open the door or snap the covers apart.
If you don't have a routine, establish one like Laurie A described. You have to set the tone, expect her to comply, and not give in, consistently. I can't say how long it will take, that depends on if you stick to it and let her know this is how it is. But I can say that routine gives little ones security, they actually want and need boundaries to be set.