My little boy started dropping his naps before the age of 2. It's just something that happens, unfortunately. You can't force them to sleep if they don't want to.
I have been here myself before. My eldest son stopped napping around 2 years old and I had an infant at the same time. My husband was also working nights and I worked during the day. I feel your pain! Some toddlers just stop taking naps early. Both of my elder kids stopped napping at 2-2.5 yrs. I know it's hard but I learned to embrace the change. If it helps, put your kids to bed at the same time in the same room. I synced my kids' bedtimes to the same time and I coslept with them. You may not get a lot of sleep with 2 kids in your bed, but it's much easier than going from room to room trying to put 2 kids down to bed, especially since you are alone at nights. Hang in there, you are doing great!
I have a 26m and 3m, so I'm in the same boat. If you have the energy to take her out, I would highly recommend it. Libraries, park, indoor playground, zoo, anything that will help get all her energy out. My daughter will nap for 2+ hrs after an outing. And if for some reason, she still won't nap, I try to keep her up til at least 7p and then she will randomly pass out somewhere or tell us she wants to go to bed early. It helps that my newborn also sleeps around 7/730p. So, in rare occasions, she doesn't nap, the house is quiet by 730pm, and it's actually really nice.
The 2 year sleep regression is ROUGH. I went through this too with a 2 year old and a newborn. They were constantly screaming, tired, and we were all crying. I honestly think the 2 year sleep regression is literally the worst one. It gets better once the regression passes 💕