I'm sorry but my answer probably won't be any help for you.
tl;dr I was diagnosed with sleep apnea a number of years ago and got a CPAP machine. I stopped using it after about 8 months but... Since I sleep on my side I had issues with my head slowly settling down into the pillow as I slept and causing my mask to gap because of the pressure from the pillow on the side of the mask. So I found something that worked for me. I used one of those U-shaped travel pillows. I'd set it on top of a single regular pillow, oriented upside down or backwards, so that the bottom part of the U was under my neck and one arm of the U supported my face from under ear on my jaw along the side of my face in front of my ear and my temple. The other arm of the U supported the back of my head. The end result was no way was there any pressure on my CPAP mask. Very long story short, although I don't use the machine anymore, I still use the travel pillow. So I can use any earphone, even ones that would stick out up to about an inch and I'd never have problems because the area under my ear isn't touching my pillow.
Having said that, I'd suggest something small like the SoundMAGIC PL50 or similar style designs, KZ ZST (under $20), TFZ (the Fragrant Zither) either Exclusive or Series lines (although I'd suggest the plastic shelled ones as lighter and less likely to fall out or need to be removed. The metal shelled (in the $100 range for these) King, Exclusive 5 and Series 4 all get good reviews here. The plastic shelled ones are less expensive and still get decent reviews). I've used the following personally, although remember my caveat above, SoundMAGIC PL50, KZ ZS5 and ZS6, TFZ Exclusive 5, Brainwavz B150, Senzer High Resolution, Marshall Mode, Mee Pinnacle PX, A151 and M6 just to list some of the IEMs I've been experimenting with the last few months.