Hello jfrombk,
I completely understand what you're feeling. My husband and I recently got married (this past June) and I had all those feelings. Heck, i've had them on and off for a good portion of our relationship. But it always came down to, I love him, I KNOW I love him even if I can't feel it at this precise moment. When I'm depressed, I don't feel much of anything, especially not positive things. Eventually, it swings back the other way, and I'm filled with intense love for him, it feels like I'm about to explode. I think the majority of the time is spent some where in a content middle ground. I used to feel intense guilt and shame when I couldn't feel things until I finally told my husband. He said he understood, at has even felt the same way at times when he gets depressed (he wasn't diagnosed, just going through situational depression).
Keep thinking positive, keep looking forward to your wedding, and remind yourself of all the things you love about your fiancee. Tell her you love her. Make her something or buy her something to take your mind off worrying about depression getting in the way. I know it's easier said than done, but don't let it get in the way. Do everything you can to keep the focus on positive, loving feelings.

Take care and congratulations!!