I had Lula spayed at exactly 6 months and she was just 3 pounds but also spaying is a more invasive surgery than neutering. I actually discussed the surgery at length with my vet and made sure she had spayed puppies as small as Lula many times before.
As long as you have a vet you trust the main thing you need to decide is whether or not you plan on breeding. I was SO nervous the day of Lula's surgery so worrying is 100% normal!!
By the way I had a feeling by the name Jacoby you must be from boston!!
Are you by any chance a sox fan??