It could be an oversight from ur care provider u can politely call his/her attention to it.

Normally, 3rd dose of T.T is to be given 6 months after d 2nd dose. 4th dose a year after d 3rd dose, then d 5th a year after d 4th dose. U are suppose to have maximum of 2 in pregnancy like ur friend said. But note that it wont have any negative effect on ur baby. Cheers and relax!