Potty training questions....

My daughter turns 3 tomorrow. We started potty training her a week ago. I had tried before with pull ups and stuff but nothing ever stuck other than a few random pees on the toilet so last week I decided to take away diapers and pull ups completely and try out the 3 day potty training. The first day she had more accidents than times she made it even with me setting 15 minute timers to bring her to the toilet, the second day she did a bit better and at least made it more than she had accidents, by the third day she only had one accident first thing in the morning and hasn’t had a pee accident since. The second day she also went poo on the potty twice but the third day she had a poo accident, I got her all cleaned up and just explained again about going poo on the potty and told her to go on the potty next time. Now it’s been a couple days and she hasn’t gone again. Today she keeps telling us she has to go poo but when we bring her there she doesn’t go and says she’s done after a minute or two. I’m wondering if she feels like she has to go but is holding it in? I’m not sure why because she did it successfully twice before. Has anyone else’s kid done this? What’s the best thing to do? I keep telling her to try but she still hasn’t gone, however she’s doing great still with peeing. Thanks in advance!