I know several people who had one baby on Clomid.
There is a way to assure you have one baby, but your doctor may or may not go for this: if you have an ultrasound before you ovulate, you can see how many follicles you have. If it's more than one, then you can skip trying that month. (Someone below said that a large follicle could turn into multiple eggs, so that's something else to consider.) The ultrasound may not be covered by insurance, and your doctor may tell you it's unnecessary (although some do them at this time), but it gives you a warning that multiples are possible if you go ahead with the cycle. It may take longer to get pregnant this way, because you're skipping months, and only letting yourselves try when there you think there's one egg.
Doctors try to give you just enough Clomid so that you ovulate. Chances are that he/she will start you out on the lowest dose.
Good luck! I took Clomid for aeveral months too, but then we realized that I had 2 blocked tubes, so that's another story. I hope it works for you and that you have only one baby!