Holy crap, that's beautiful. Normally I tend to avoid anything too sexual in the HP fandom, because well, most of it is horrendously NOT canon. But this is absolutely canon, and incredibly well-drawn to boot. The realistic bodies and poses, the great perspective... the color gradiant and 3 seasons is a great idea, as is showing Molly pregnant (as she spent a great deal of her middle life pregnant, no doubt...)
The last, later-in-life section is my favorite. They're holding each other so tenderly, it actually makes me feel all warm and fuzzy inside.
Beautiful.