Unfortunately I can't speak for every other reader, but I'm under the impression that yeah, daily posting is not optimal. Personally when you start following a bunch of comics at the same time, if you don't check your computer everyday, coming back and finding your feed full of stuff to catch up on can sometimes feel like a chore.
My humble suggestion is not to post everything in one go, but switch to posting twice or thrice weekly, and maybe post 2-3 comics in the same update. That way your subscribers still get fairly frequent content but not as much nagging.
(Oh, and I gotta add, losing subscribers at some point is kind of physiologic. As you continue your comic, people who signed up at first who didn't know what it was going to be about might realize it just isn't for them. It feels crappy, but don't take the sub count to heart too much; it's not worth it.)