nap time help please!

My daughter is 19 months. She sleeps at night 8-8 usually. She starts acting sleepy around 11 am for a nap. I try putting her down but she won’t go to sleep. I’ll go in and check on her sometimes she’s poopy so I change her. I’ve tried keeping her up longer and putting her down around 1 but same thing. It will end up being a 1-2 hr ordeal trying to get her to nap then she will barely sleep an hour 😩 I don’t get it bc she acts tired! I’m pregnant so really want her to nap still. But it’s so stressful trying to get her down. Anyone else going through this or have advice?