I saw my doctor and nurse a couple of weeks ago (3 weeks after my IVF BFN) and they said I could go ahead next cycle. I just had to ring my nurse and let her know when AF arrived and work out when I would start the OPK's. She didn't mention anything at all about having a longer break, or that my cycle might not be normal. I'm a bit annoyed actually. I think I will give her a call on Monday and let her know what's going on and asking if I should wait until I have a normal length cycle again?!