No periods. Affect me if i get pregnant?

I was due on 22nd January & I haven’t got my periods yet. My periods have never been regular. Since a few months I have been on a treatment where I was asked to have primolut to regularize my cycle. And Since October last year I started having 28 day cycle. During the December month, I just had one tablet of Primolut & I got my periods as per 28 day cycle. Last month, ie in January I did not have any medicines & now I still haven’t got my periods. I am trying to get pregnant & we have started trying since this last month January. I took 2 pregnancy tests at home & both were negative. My question is what should I do now? Should I have primolut medicine again to get my periods & if Yes for how long do I have to continue this medicine? Also will primolut affect me if I get pregnant? Currently I am on hypoThyroidism medication - 100mg thyroxine.