Dd is just 2. Until recently she'd reliably go down for a pm nap of 1.5-2.5 hrs with a bottle of milk in her cot. But in recent weeks it's got harder and harder and she's missing naps 50% of the time. Strangely she always seems to sleep at the childminder's.
She also take forever to go to sleep at night - regularly takes 45 mins-hr for her to fall asleep, with us in her room.
I'm not ready to lose naps and I really am sick of being stuck in her room til 9pm every night....
You being in the room may well be the reason for her taking ages to go to sleep at night.
While children often like Mum or Dad there for reassurance purposes, it is a double edged sword. She will be going to bed and lying there anticipating you leaving the room. She doesn't want you to leave so she tries to stay awake as long as possible so that you stay with her as long as possible.
If you break this habit, so that she knows you will say nan night and then quickly and without any fuss leave her alone - she will initially hate it. However once she learns that there is nothing to be scared of going to sleep on her own, she will then have no reason to stay awake once going to bed.
This is all a separate issue to lunchtime naps though. You don't stay in the room with her afternoon naps? It sounds like she is starting the transition to dropping them.
Don't worry, they don't just stop all of a sudden. You might expect a 6 months transition when some days she'll have a proper nap, some days she'll fall asleep on the sofa but not go to bed at naptime and some days she'll stay awake right through.
I would sort bedtimes out first, then see what having a proper bedtime where she goes straight to sleep does to her lunchtime nap.