Don't let your husband and daughter team up on you, he shouldn't be bringing her into the discussion (if he is). That being said, don't discount either of their opinions.
I think you should tell your husband thet each of you should make a list of everything you think would be involved, pros and cons, of all aspects - emotional, physical, financial, etc. Include who would be responsible for what baby-raising tasks, how it would affect vacations, your living space, any topic you can think of - give him all the angles you want his list to include before-hand. Then set a time period to come up with the list, and a specific time when your daughter will not be present (no other distractions allowed, either) to compare lists and go over your feelings.
I am 42 and have a soon to be 7yo. While I personally would, most of the time, have liked a 2nd child, and I DEFINITELY feel it would be better for my daughter to have a sibling, it never happened, and I didn't want these things enough to pursue fertility treatments for them. Mainly because, for all the good, a baby would bring, it would have brought financial difficulties (manageable ones), it would make it harder to travel, and my husband is 15 years older than I am, and the first baby was scary enough for him. So, in our case, he was the more-reluctant one.
I think you have time, if you decide together that a 2nd child is the right thing to do. I DON'T think you should wait too long making your decision, more because if you decide yes to a new baby, you don't want the gap between the 2 kids to be too great. (you want her to have a playmate, not a living doll). And, if you decide no, at least if you both go through this exercise, you should have a far better idea of the logic behind each others thoughts.
Best wishes