S.B.
I know this is a little different but it might work. We put a clock in his room, the kind with big numbers and since he knew his numbers we told him that he could get up and come in our room when the numbers on the clock said "7 3 0....meaning 7:30". We found that he was always coming into our room to ask us if it was time to get up, or he saw the sun up and thought it was time to get up. With the clock in his room he just waited in bed until it was 7:30...although we told him that if he had to go potty he could get up and go, but then he must get back in bed until his clock said the right time. We started that about age 4 and even to this day we tell him what time he can get out of bed and he respects that...if not he would be up and running around the house at 6 and waking everyone else.
You might even want to try and let her sleep with something special that would remind her of you and tell her that she can only have it in her big girl bed if she stays in her room all night. But that if she keeps coming in your room she wont be able to have that something special.
Just a thought...I hope things work out for you. Your not a horrible mother...we all just have days like that sometimes..but it's just a phase that will soon pass.