Advice on how to spar politely

Just started up Muay Thai. I have some past striking experience, but I’ve never done it enough to really move past the beginner/early intermediate phase. I’m also currently overweight and I’ve never had great cardio(past lung injury), and I have a reconstructed joint along with other injuries from wrestling so I’m very physically limited.

I’ve been going to Saturday sparring, and everyone there usually is much more experienced than me. I can’t help but feel like I’m doing everything wrong in a way that’s maybe annoying people because it feels like some of the guys are going really hard on me despite my inexperience. The crew of dudes who went to Thailand together and the coaches are really chill, but everyone else is beating me up.

I do land a a good bit in the long mid ranges because of my long arms, but I’m so gentle people tend to just walk through my shots, cut me off, and batter me even when I’m landing 2-3 clean shots before they get in so clearly I’m not being overly forceful. Its also pretty clear I don’t know how to fight once I’m really pressured so I don’t get why they won’t slow it down. Maybe they’re trying to help me improve there and I’m taking it as them treating me like a heavy bag?

I the gym has a lot of lighter weight fighters and although I’m not particularly strong I’m fat and explosive and I’m worried that if I move even at half force that it will hurt them and create a cycle of escalation. This was an issue when I was younger and smaller, and I imagine if I did it with this extra weight I’d end up getting my ass kicked by a real fighter.

A. What are some common things I might be doing to bring this on myself?

B. What polite ways can I approach the subject of slowing things down so I can build my comfort level and learn both technique? Also that due to my injuries they should probably spar me like I’m 40+?

C. Is there any advice, or ways I can train to be better at moving with speed gently so I can pick up the pace without knocking heads back?