Synthyroid and missed period

My story: my husband and I are actively trying to become pregnant with clomid and IUI. However this time around I was placed on Synthyroid due to antibodies but normal levels.  We did clomid, IUI and Synthyroid for two months and nothing happened, I came on my period both times. During those times and prior my cycles were 26 days apart. However now I am in my third month, I stopped clomid and only taking Synthyroid and had lots of sex during my fertile week also had a ultrasound and dr saw a 17mm follicle, this was with no medication (clomid)I am now 4 days late for my period. I feel as if I want to start my period but nothing. I am having cramps, bloated, sore breast, and fatigue. FYI were trying for our second child. With our first child we got pregnant with clomid and IUI on the first try. What do you all think? pregnancy or change in cycle due to Synthyroid?