A couple of things my dentist told me:
* First, the others are right, you are brushing too hard.
* That normally means you don't do it right...
* Flossing is good, but normally not the cause for bleeding gums
* Although instinctively you would do the opposite, especially when your gums bleed you need to brush them nicely.
Advice on top of everything: Get one of those rotating electric toothbrushes. I have used one forever, and the lack of cavities and my cleaner teeth are well worth it. Oral B plaque control is the one most people I know use, but I am sure there are others.
Electric tooth brush: $40
Dentures: $5,000
That smile on your face: priceless.
Edit: Oh and yeah - what the other guys say: See your dentist!!!!!!!