I know the feeling.
Make sure all the files in your gallery are compressed hard. Especially the thumbs. Do play around with different sponsers but if nothing seems to be working, maybe reduce the size of the gallery some (I don't know how big it is - maybe you could post it here) but, if you do, also remove some banners/ads to keep a nice thumbs:ads ratio.
If the gallery is submitted elswhere too, check their rules first so you don't get blacklisted by changing the gallery. Most TGP owners are pretty cool and they'd probably understand your situation. They mostly don't want cheaters to change the galleries to all ads or redirection or adding BS like autobookmarks etc after accepting your gallery. Just keep their (and your) surfers in mind as you tweak things around and don't transmogrify your gallery: try sticking to what was accepted in the first place.
Wish I could help you out with the bandwidth portion, but I was in a similar situation earlier this month
so there's none left on my plans included.
Most important...
good luck!
