Welcome to Ask The Doctor.
No, you can't get pregnant while having sex during your pregnancy period. You have not mentioned the reason why you are suspecting pregnancy, but in case you are not getting periods after delivery then you might be having Lactational Amenorrhea.
This is natural. You will soon resume your periods. Make sure that you play safe during this period also.
Share my opinion with your doctor before you act upon it.
I hope it helps.
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