Bad sleeping habit... 🙈

I am a FTM and my fiancé works nights and I work full time. My little guy is 12 weeks and is the love of my life. About a month ago, I would have trouble getting him to fall and stay asleep so I started letting him lay on my chest (on the sofa)- no lecturing, I’m aware of the risks 😔. Well now it seems he will only sleep on my chest and if he falls asleep elsewhere, the naps/sleeps are short lived. So my question is, please give me suggestions to break this bad habit. The habit has continued because it’s been the only way for me to also get some sleep.

I have started using the arms up swaddle, as he grew out of his newborn Velcro ones. He seems to love the arms up, it’s a super thin stretchy material. I have the Merlin sleep suit, and I’ve tried three nights and he hates it. I think he gets too warm. Ideally, I’d like for him to sleep flat in the pack and play (next to my bed). I also have an auto- rock and play.

Please help!