Anyone else struggling with bedtime?

Ma

My December 2016 was a champion sleeper. She would nap 1-3 and then go to bed at 7. She went down with no fuss at all. We switched her crib to a big bed and everything was fine. Then she potty trainer herself. Then like 2 weeks after that she lost her freaking mind. So at bedtime she’ll scream and cry for HOURS. Well go in and snuggle a little bit or take her pee but then she’s right back to screaming. She won’t go to bed until like 9. I am at my wits end with her, I’m like legit pissed off. I want to take away her nap but I think she still needs it because she is always a cranky mess. I need help!!!!