If they are only two days old I don't think you have a problem. Before they hatch they absorb the yolk. They can live off of that yolk for three days, that's why they can be shipped. Just because they don't have to eat or drink the first few days doesn't mean they won't eat or drink. It doesn't mean that eating will hurt them, it won't. But they don't necessarily eat much when they do eat. They are just not that hungry.
Another thing is that they are small. Their crop isn't that big so it can't hold a lot. As they grow their appetite will increase dramatically.
I've noticed when a broody hen hatches her chicks and first brings them off the nest they spend a lot of their time under her instead of running around. When I move chicks from the incubator to the brooder they tend to spend a lot of their first few days huddled close to the heat instead of out running around. I think it takes them few days to get used to not being inside a shell under a hen as far as regulating heat. But they make that adjustment in a few days.
It sounds like you are using a heat lamp for heat, I do too. My brooder is outside in the main coop so I can get some pretty big temperature swings. I've found that chicks straight out of the incubator or from the post office are very good at regulating the heat if they have an option from warm enough to cool enough. It sounds like that is what is going on with yours. They are not directly under the hottest part but close enough to be comfortable.
If they are uncomfortable they will give a plaintive peep. It's not that happy chirpy peep but a really plaintive type of peep that tears at your heart. If you ever hear it you will immediately recognize something is wrong. It might mean they are cold, thirsty, or hungry. I've only heard that a few times. Once a chick never learned to drink from watching the others or from me first dipping its beak in water so about the 4th or 5th day it started that plaintive peeping. It took that long for it to really need to drink after it used up the yolk. I dipped its beak in the water (not sure how I figured out to do that) and it just stood there drinking for a long time. A few times I've had a chick get separated from a broody hen and trapped where it could not get back to her. It started calling her with that plaintive peep. My point is that if you are not hearing this plaintive peep you are probably doing fine.