First off, get a light on that shotgun, you want to positively identify what you may be about to shoot. You don't want to be juggling a flashlight or waving a hand around looking for a light switch-that might not do you any good.

You definitely want buckshot, then look at shot size. The Federal H132 Flitecontrol is the low recoil 00 buck. HOWEVER, they also make it using #1 shot. There's a significant difference in shot weight with 00 being just shy of 1 1/8 oz and the #1 close to 1 1/2 oz. I'd expect the payload on the minature shells to be lacking for defensive use. The #1 load was developed at the request of a number of tactical teams, gives less penetration of walls etc, and a greater shot density on target. If you can't find these locally, Streichers Police Supply stocks the stuff and sells to anyone. If backordered, they will deliver as soon as they get it.

If you think you somehow might need slugs (and have rifle sights adjusted for their use) a side saddle or stock cuff could hold a few.