I won't point out the story lacks a story (which it does in spades) because you've warned the reader in the description. So I'll comment on the smut aspect.
It sucks.
It was incredibly rushed and lacked any detail whatsoever. One minute, Harry's standing there, the next he's forced himself upon Bellatrix while Narcissa masturbates, and then he ejaculates. It wasn't exciting, appealing, or arousing. Not in the slightest. Dull and boring is the best description I can give.
Take your time, add details and descriptions, not only for the lemon/smut scenes, but the whole story in general.