Wa alaikum salaam wa rahmatulahi wa barakatuh,
There are no prescribed amount of days that you need to wait before you have sex with your husband after delivery. However, it is not permissible to have sex if you are still bleeding.
It is possible that women may bleed for up to 2 or 3 months after delivery and this is perhaps why some people say to wait this amount of time.
If you have stopped bleeding and 2 or 3 months has not yet passed then there is no harm in having sex. There is no way that it could harm your baby. This might be a cultural argument, but medically and Islamically is not true.
If you wish, you should confirm this with a reputable religious scholar who can advise you on this also.
May Allah make your baby the coolness of your eyes in this life and the next.
Disclaimer: The conceptualization and recommendations stated in this response are very general and purely based on the limited information provided in the question. In no event shall AboutIslam, its counselors or employees be held liable for any damages that may arise from your decision in the use of our services.