Losing my mind

Just as the title says... I honestly have no idea how to entertain my three year old. He has zero interests in any of the things that toddlers usually love to do. He does no individual play. All he ever does with his toys is lay them out on the floor so everything is a big mess and that's it. No interest in painting, drawing, any of his toys. Nothing. I tried to get him into these things by showing him but it doesn't even last a minute. I'm at a loss here because it's causing me a lot of stress. I watched some YouTube ideas on how to do these fine motor skills with him and he's not interested in that. He loves to play with water and going out in the garden that's about it.

It's just becoming so so hard for me. And I keep losing my temper, as I don't know what to do with him. He has also started refusing nap times. He's super tired but he won't sleep, which leads him to be super cranky and he throws a tantrum every 5 minutes. I'm also pregnant and I'm finding this extremely overwhelming.

Anyone else going through this? Pls help me out