It is normal. While you are pregnant your hormones cut down on the hair that is shed daily, which is why people say their hair was so much better and thick when they were pregnant. Now the hormones are changing and you are losing the "old hair" that your body held onto. I think it took about 3-4 months after birth for my hair to stop coming out so much and get back to pre-pregnancy levels and fall out rate.
When I say I was shedding, I have a little wad in the shower now, but back then, Lord It would completely clog the drain with a wad the size of your palm. It was horrible. It would come out in handfuls, I was sure I would be bald. I never was. The first child this really alarmed me, but my doctor told me it was normal. And it happened to me with each child, Total 3 times. So by then I knew what to expect. Take your pre-natals and make sure you eat well. You can talk to your doctor on your next visit, but I wouldn't schedule a special appointment. The pre-natals won't stop it, but will make sure your body can replace and have all the nutrients needed.
Good luck,
L.