Confused?!?! Irregular cycles!

Corrine
Me and my husband have be TTC for roughly 15weeks now, I was on the implant for 6years(replaced after 3years) I then went on the pill for 6months, my periods havnt really been regular for years, working out between my last 2 periods I have a 42 day cycle (I think, new to this!), I have been feeling really sick, dizzy and tierd along with headaches for the past 4ish days and have been abnormally emotional, hopefully not making symptoms up in my head!!, do I test if late after a normal 28 day cycle which would be the 31st? Or wait untill my 42 day Cycle, not sure if I'm making any sense, proberly just getting my hopes up.