one baby and done?

How did you all decide that one baby is/isn't enough for you?
I have a 5 month old and I'd love to have another one, but my SO doesn't. He's talking about selling and giving away our baby stuff (clothes she's outgrown, swing, bassinet etc) and I'm just not ready to make this decision.
I would love for my LO to have a sibling asap, I would love to be pregnant again, heck I'd even love to go through labor again. My hubby is significantly older than me and says he's done with this one, we should just enjoy her and give her everything we've got to give. I totally get this point, but I believe when she's older she would be much happier with a sibling. My husband also believes that everything is way easier with one (going to places, find a babysitter), and I can't argue that point either. Because of his age it's not a "let's see how he feels in 5 years" thing, it would be now or never. 
How did you decide if one was enough? Do you regret your decision? Do you think it's selfish not having more than one because it's easier for you?