Could Missed Period And Lower Back Pain Be Signs Of Conception Or Side Effects Of Susten After HCG Shot And Letrozole?

I am 33 year old and trying to conceive from last two years.my all report are normal .after giving multivitamins and letrozole 2.5 for 1 year my doctor give me HCG shot on day 13 and after 3 days susten 400 twice a day.i have regular 28 days cycle but this month I don t get period on day 29 and there is lower back pain from last 10 days.is this is symptoms of conception or side effects of susten 400