Metformin

I have been on metformin for a month now and I have been regulating on my own my past three periods were Oct 21rst Nov21rst Dec 21rst... started metformin the end of December i just came on my period the 18th! So i now have a 28day cycle went from 30 to 28...

However we did have sex but nothing happened my bf is suppose to get his sperm checked but hes acting like a kid going to the doctor but he's willing to go. I really think he's playing a role in this since we've been together for 4yrs nothing has happened

My question is should I wait another month to ttc or start this cycle since I have been pretty consistent on my period