Welcome to Buffy Boards! Your story sounds a lot like mine, didn't catch on to Buffy till it had already been canceled, but I'd catch the odd epi on cable here and there. I started somewhere in s5, and ended up renting s7 because they weren't showing them fast enough for me! Bought the seasons shortly after that and the rest is history!
It's not complete without Angel, tho....glad you're on to that next!