I feel a bit ungrateful here as I am dismissing so many good ideas, but I have honestly tried them
You are NOT ungrateful Ryn! You need to parent according to your own values and standards (i too wouldn't want to use a lot of "props" she has her bedtime lamb and that's all) it's bad enough having to listen to "i told you so" from MIL/your mum/strangers without hearing yourself saying it to you in your head as well!

I realised after i answered you that when it comes to sleeping i am strict and relentless. During DD's 90 minute morning nap i usually shower, tidy, prepare lunch and surf about a bit. It is undivided "me" time. DD woke up 40 minutes early today but you know, i was busy tidying, and she was fine in her cot with a cup of water and her lamb and a toy seal, so i went in once, tucked her back in and told her it was naptime and then i ignored her. She didn't cry or sleep, just moaned a bit, sang a bit, whinged a bit, chatted a bit, off an on. Ultimately i went to get her when i was finished doing what i was doing. I am more comfortable with this than with living in a filthy house and never having a moment to myself.

Obviously your DS is a lot younger than DD and he might not be ready for this approach and would scream in distress, but i honestly think HALF of DD's cooperation is actually through lack of choice! LOL.

Anyway, i'm not sure what the point of that was except to say that even if i think DD naps and sticks to her routine etc. in part at least it's because i accept no alternative. You have tried everything Ryn, this is not something you're doing or not doing, it's just the way DS is right now.

hun, be gentle with yourself and grab your sleep when you can.

Bx