K.,
I believe it's normal to feel like you do. Remember, you've had 2+ years with your first child so it's hard to imagine loving your second as much. It won't be long before your emotions take over and you'll feel as much love for your second as you did/do for your first.
Some ideas that may help...
*be sure to spend some good quality one-on-one time with your first, maybe when your second is asleep. By spending time with your oldest, without distractions, may help you focus on your time with the newborn when you need to.
*maybe try the skin-on-skin contact with your newborn. Let him lay on your chest and relax. Sit in the moment with him and enjoy it. This was one of the most special times I had with my daughter when she was a newborn.
Finally, if you are feeling out of sorts in other ways (post partum depression) then go to your doctor. Don't risk your health, or the health of your children, out of fear of asking for help. Remember, what you're feeling is normal for some women. Not everyone gets the warm-and-fuzzy feelings right away, especially with the second, so give yourself some time.
Good luck!