Hey N&J,
At 5mths Sofia did not always yawn or rub her eyes to let me know when she was tired. You actually have to be with her every second to catch the yawn. So maybe your LO is yawning but you missed it. It is totally possible.
As they get older, they make it very obvious to you that they are tired. You want to put them down for a nap before it turns into overtired. This has happened to me once or twice. Once they start crying you have passed the window and it gets harder to put them down.
Sofia has always been an independant sleeper, so what I do is put her down in her crib and check on her until she is asleep.
If you stick to your EASY plan then you will know when she is ready for a nap. Sofia did not always follow it either. I used EASY as a guide. It was never set in stone for me. That is what I tell pp all the time. All babies are different.
Good Luck
Dree
p.s It isn't dumb to ask questions no not matter what it is.... Information is power. You are being a good mommy.