Yeah. I've been having that problem, too. I generally just play a mission in single-player and try it afterward. It'll get really old when I run out of single-player missions, though.
When I do manage to connect, though, I do some damage. I played for three hours yesterday and got the Ace pin more often than not. I was almost always several hundred points above everyone else. Here's some tips for playing as a medic:
Drop a medkit on anyone who looks like they're holding a position. Especially if they are in your squad. If you can get a medkit into a group of squadmates who are taking fire, you'll get hundreds of points in no time.
Revive everyone. All the time. not only is it awesome free points with hardly any effort, but it makes you more likely to win the round.
Use your gun. If you're carrying an LMG, they are generally SERIOUSLY accurate. I have picked off snipers just by aiming under a spot triangle and squeezing off a few bursts.
I love this game. LOL