Hello and welcome back to BW

From what you've said it sounds to me like your DD might actually be UT (under tired) for some of her naps rather than OT (over tired). The two are quite difficult to tell apart so it's easy to assume OT.
After about 4 months LOs can show the tired signs when they are bored (rather than tired) and need a change of activity. Moving to a different room or offering a change in toy to hold, looking out of the window together and chatting about what's there might be better than taking her straight to bed for her nap. You might be surprised how she perks up and isn't tired for another 30 mins or possibly even more.
LOs can also come to expect a nap at a certain time (or after a shorter length of A) due to habit, so you might find if you push through for a few days her mood improves.
When LOs are UT they can fuss and resist at nap time, trying to communicate that they are not yet ready to sleep, this is often assumed to be due to OT and as a result the A times are kept shorter rather than extended. If you try out the change in activity and extend the A time (to 2hrs, 2hrs 15 or 2hrs 30) you might find she is less resistant going down for the nap.
The times you find she is easier to go down could be when she has had a short nap previously meaning she had less energy for that Activity time.
UT naps are typically limited to the length of one sleep cycle, 40 mins, which is another indicator from your information.
You might need to feed mid-A time rather than directly after a nap for some of the naps to fit in the E times if they are shorter. You might though find that she will happily go a bit longer if she is asleep (ie if 2.5hr E is going to fall at 1hr into the nap she might just sleep 1.5hr and eat after 3hr instead - hope that makes sense).
I'd like her sleeping more reliably for long naps in day
Although the basis of EASY is watching LOs cues, when a routine change is needed watching the clock can be more beneficial - the routine changes are still in response to LOs cues really but from the point of view of the bigger picture.
wouldnt mind her being in bed earlier rather than later.
This would probably involve being a little more firm about when BT and WU are. You might need to wake her in the mornings to get onto a more consistent routine.
Hope this helps