My little ones are 16 months apart so I can relate to where you're coming from (all of you NEEDING nap time) and my daughter wanted to start potty training just before she was 2. So while I don't think your daughter is too young to be potty trained, you sound a little exhausted so it might not be worth the extra frustration for you to go all out at this point. However, you might want to try transitioning her into it. There are a couple of things you could try.
You could see if she'd like to go potty on her own before nap (you know the whole routine). If that doesn't work, you could try initially laying her down but then go back in her room after a few minutes (once she's gotten comfortable) and take her to the potty then. If neither of those work (or sound appealing) and you think it's really a play for attention- if she's not complaining, just leave her. Of course this depends on how sensitive your daughter's skin is. Another thought is you could try a group nap. It may sound daunting but if she's looking for attention (she may think she's missing out on something) it may work and it will give all of you the rest you need. It may take some getting used to but this still works for me. Once everyone's been fed, all three of us got into my bed for story time followed by nap time. The first couple of times I did need to remind my daughter that it was nap time and if she couldn't behave in my bed, she'd have to go to hers but it's such a treat for the them that they comply fairly quickly. Plus they love knowing that they get snuggle time with me and they know they're not missing out on any action. I love the uninterrupted snuggle time and that I get the rest that I need to recharge! (And because we get to do this together at nap time I don't feel so guilty enforcing the rule that they can't join me at night.)
No matter what you find works (or doesn't) for you the good news is - life with two little ones gets a little better and easier every day!!