I think most med students question their decision at some point during the first two years (okay, maybe daily for some). It's natural to wonder if you are doing the right thing, esp. when the first two years consist primarily of flat-out, boring-as-hell memorizing and regurgitation. Studying for Step 1 right now really makes me question it. But the bottom line for me is knowing that there isn't another profession i'd rather be in. Believe me, i tried to make a go of it doing other things, but nothing could hold my interest like medicine does. I'm aware of all of the issues involved in being a physician, and i'm not sure i could enthusiastically recommend the profession to someone else. But for me, it works.
I was dissapointed with second year, but i think that's mainly b/c i was told repeatedly about how 2nd year is better than first. True, definately, but not by as much as i built it up to be. I hear the 3rd and 4th are better than the first 2 so i am hoping that prediction carries a little more merit.
I guess the bottom line is that most people probably get discouraged and wonder what the hell they are doing in med school. Most end up graduating and just look back thankful that's it's finally over (i imagine, not having been there yet). But hopefully, the journey isn't that bad, and you'll have some great memories and a wealth of useful knowledge. And as others have pointed out, doing poorly in a class or on boards doesn't eliminate you from the game. Failing doesn't either. Plenty of med students struggle, most still become physicians at the end. First year grades especially don't count for as much at the end, unless they're good enough to get you into AOA.
I sincerely hope school gets better for you as you go on. Just know that you aren't the only one having these thoughts/feelings.
Sorry for rambling on and on. I am desperately trying to procrastinate my Step 1 studying!!