No period

Nicola • Married. 29 years old. Mmc at 11 weeks July 2015 and mc at 4+3 weeks Nov 2015. Pregnant with baby girl due 30.07.17 ♡♡
I haven't had a period since 21st Jan. I'm now 10 weeks late. My cycles are normally 28-35 days. I'm ttc but had negative pregnancy tests and blood tests. Dr has checked my hormone levels for pcos etc and my thyroid and everything is normal. Why haven't I cone on?! I just want to come on so I can start ttc again x