Naptime?

So I'm kind of on a "see how the day goes" nap schedule with my 3 and a half year old. Lately Bella has been up talking in her bed until 10-10:30 sometimes, even though I only let her nap about and hour and a half, so I was thinking she may be done with nap time. But then there are days where she definitely needs a nap, so like I said, "see how the day goes" nap schedule. It has been working pretty good. If she doesn't nap she has quiet play time in her room. The rules are that she plays quietly in her room, she can't call for me or come out except for the potty, and she stays in until I come to get her. She has done really well with this, although some days I discover that it should have been a nap day. Like days where I go and check on her and find this: