Cat not adjusting well

It has been incredibly hard to adjust to my cat living with me and my gf, and I don't really know what else to do. Before I lived with my gf I was with my dad still, and my current cat Cheese, had allot more space. He could roam a 3 bed 2 bath and a catio and now were in an apartment but live with a roommate so he can only be in our room.

He also additionally had full access to 5 bowls of food all the time at my dad's place because we had 5 cats there, and when i moved out I wanted to focus on food quality and feeding schedules.

He is a very clingy cat as I got him during the pandemic and so I was home 24/7. If i leave the room he screams. No attention he screams. Wants a snack he screams. If he's not screaming hes trying to get into something.

My gf has tried to treat training him like a dog but cats dont learn like that so he has started to just associate her to being mean. My gf now hates him because at night, he will go on the bed and scream in her face until she wakes up. He will wake her up multiple times a night and this is because she is on the outer part of the bed closest access to him, and he wants food.

I've tried giving him 2 meals a day with one am one pm as well as 2 snacks throughout. Helped some but he still screams. I tried playing with him, tried calming treats. Try to give him more attention and love and etc.

Its so stressful not knowing how to calm him and make it so my gf isn't angry or stressed either. I dont want to leave the room and he screams either. Besides the roommate he cant leave the room due to bug killing tablets that can harm him if he eats them.

Truly I don't know else what to do. I didn't notice how spoiled he was at my dad's and now I can really tell.