How old is the baby? I was told that they are comfortable when we are. Relax, not everyone's perfect and you'll have times when you screw up, it's normal. I would dress him in one layer warm clothes, a jacket on top. Take blankets if he's a little one and that will keep him warm enough. I think he'll be fine as long as it's not snowing or anything like that. They have the same signs we do, goosebumps when cold and sweating when hot...just check him if your worried :)
I know what you mean. The last few days I've put Brady in a t-shirt onsie with a lighter long sleeve shirt on overtop and then put a heavier sweater or his coat on over that and then if it's really warm out then I just take the sweater or coat off. It was really warm yesterday here and I even had his winter hat on! LOL DH told me to take it off, he's already warmer as it is so it's a good thing cuz he was eventually sweating!