Hi, Usually the effect of the injection lasts for 3-4 months. The effect can last longer because the microcrystals of depot injection sometimes dissolve very slowly. Therefore the period can be delayed up to 6-7 months. The symptoms you have mentioned can be due to the progesterone effect of injection too. To clarify things take a blood pregnancy test as it is more sensitive than home pregnancy test. If it is negative don t worry. Start using barrier method of contraception until you start your period. I hope I have answered your concerns. If you have any other concern, do contact me through Healthcare Magic.