TLDR; I've tried for a year to coexist with my girlfriend's dog, and things have gotten better, but it's still not liveable for me. Is there anything else I can do?

My girlfriend and I moved in together a little under a year ago, and alongside her came her Pomeranian and two cats (in addition to my own cat). I've had a lot of difficulty adjusting to this dog over the past year - especially only ever having kept cats in the past - but we've put a lot of elbow grease into making things better, and have made a lot of progress.

The problem I'm facing now is that, even with remarkable behavior improvements and a year to get acclimated, I'm still having a lot of trouble coexisting with this dog - and I'm worried we're running out of options to make the situation any better.

First, things that have gotten better:

• At first, he was an incorrigible barker (as Pomeranians are), literally setting off any time he heard a leaf drop outside. Daily chasing of cats, jumping on the table to steal food off plates, barking for attention whenever we leave the room, snapping at anyone that tried to touch his bed while he was laying in it. After some in-home training classes, a few months of positive reinforcement, and the purchase of a remote-controlled citronella collar, most of this behavior has subsided. Mostly.

• Part of the problem was my own behavior as well; I learned quickly that you can't admonish a dog like you can a cat. A spritz from the squirt bottle doesn't deter them, it just makes them irritated and bark at you instead of that leaf. Training classes taught me how to get him to respond to me instead of just aggravating him.

Now, things I'm still having trouble with:

• My girlfriend and I are sleeping in separate rooms because of the dog. He sets off anytime someone opens the door while he's sleeping and wakes him up, as a fear/alarm response. We've tried training him out of this, but he's overprotective of my girlfriend so we haven't had success - he's being stubborn about this one. We've tried putting him out in the hall, but he just ends up fighting with the cats, so this is the only peaceable solution for now.

• There are times I'm watching TV and idly petting, not paying attention to where my hand is going. This is safe behavior with cats - if you hit a spot they don't like, they just squirm and walk away. With the dog, if you hit a spot he doesn't like, he suddenly nips at your hand. He's never drawn blood, but it's always a rude surprise nonetheless. We admonish him when it happens, and have been giving him positive reinforcement when we pet him and he doesn't nip - but it doesn't seem to be stopping. We've also taken him to the vet to make sure there's no injury or skin irritation - it's just his way of saying "stoppit!". These are really the only "good moments" we share otherwise, so this one might be getting under my skin the most.

• Training commands can only go so far when they're reactive. He still chases the cats and snarls/barks at them, he just doesn't do it as frequently - and we can stop him a lot sooner. There's still the hackle-raising stress when he sets off. There are also still mornings that he barks when my girlfriend gets up to get ready for work - which is a problem because she gets up considerably earlier than me. He responds quickly when she uses his "quiet" command, but still - all it takes is one bark to wake me up. After months of a 6am wake-up call when my alarm is set for 8am, I'm going batty.

I'm not sure what else to do. Neither of us are willing to get rid of him - for better or worse, he's a member of the family. We seem to have hit a wall in terms of how much we can fix, and none of the resources we've tried have been able to push us past it. The lack of further solutions over the past few months has me in despair - something has got to give, and as it stands it's going to be our relationship.

Is there anything else I can do, to improve his behavior (or mine)? I'm at the end of my rope.