> When I don't floss, after 3 or 4 months, my gums start to puff up and bleed when brushed. When I do floss at least once a week, they don't.
That's effectively the very beginning of "gum disease"; your brushing of your teeth probably keeps it in check otherwise, but if you didn't brush or floss - imagine where that could lead to.
Smoking only makes the problems worse (IIRC, it makes the gums more sensitive to abrasion and tooth decay products).
It's ultimately best to brush and floss regularly, particularly before going to bed, or directly after eating. I'd say if you had to do one or the other, before bed and in the morning regularly would be best.
Something to keep in mind also is how you floss - you want the floss to go between your teeth, but don't let it "saw" into (and injure) your gums - think of it more like a toothpick.
On top of all this, go see your dentist regularly if you can afford it. Every 6 months is fine. You can get x-rays and other diagnostics (there's one for oral cancer, among other things - talk to your dentist) that can help with your overall health. I honestly believe (anecdote) that going to your dentist regularly can be more beneficial for your overall health than going to the doctor.
Though, on that last bit, I honestly don't understand why here in America they leave it up to the patient to schedule regular doctor visits. I even asked my doctor's office staff if they could re-schedule me 6 months or a year later, and they wouldn't do it ahead of time, just "call us in a year" - which of course I never did. I suck at such follow-ups, but I've gone regularly to the dentist every 6 months for the past 25+ years - because they always schedule the next 6-month follow-up for me before I leave the office.
I don't understand why it's not done as a matter of course by regular family practice doctors (though they seem to do this - I think - for children; but at some point you "age out" - or more often, leave home out from under your parent's care).