WKD DRGN

Hey all, I have a 2000 Honda Civic EX with 221,xxx miles on it. The last two times I've filled up I have noticed it only takes about 8.8 to 9 gallons but the needle will be bobbing dangerously close to "E" without the light coming on. (Don't really know if the light works or not, I never drive it that far down on gas...) So I have a few gallons left in the tank but it seems I'm on empty. Also I track my trips using the tripometer and I used to get to about 284 miles at a 1/4 of a tank left by the needle. Now it's like 234 miles and it's near empty according to the needle but AGAIN there is still a few gallons left. I used to be able to get to about 313 miles before it was really close to E and I would have about a gallon and a half left still. So with this poorly given information what could be the problem?? Also, I think it's been about 2-3 years (and a lot of miles!) since I've done a tune-up, could it simply be time for a tune-up again? Thanks in advance.

-Kristy