13 months, new nap problems! Help!

[PintOfBovril]

Hi all. This forum has been such a great source of advice and support to me. Yet again I need your insight!
Our 13mo settles himself at bedtime and tends to sleep about 6.30pm or 7pm(ish) to 6am with one or two wake ups for a cuddle and a quick breastfeed.

Naps are a mess. He sometimes takes 2 short naps of about half an hour each (this happens at nursery where he is twice a week), sometimes refuses the morning or the after lunch nap, sometimes takes two micro naps, sometimes screams the house down trying to settle, sometimes needs me to walk him in the pram to sleep. It's so unpredictable. Can anyone help with a suggested schedule?
I have tried the Ferber approach of going back in to soothe him and reassure him. I've tried leaving him to have a grumble. I've tried him on one nap a day to see he is ready for that transition. I've tried different spacing of the naps. Nothing seems to work. I'm really worn out by it, I suffer quite badly with depression and anxiety so my own sleep is all over the place. Any help greatly appreciated!!