Cycle change

My periods have always been pretty regular. Normally a couple days over or under is when I will get it. This month I didn't get my period until over a week after it was due, which of course caused my cycle to be 40 some days long. Normally my period lasts 4 days at the most, this period lasted 6 days long. Now, I'm not sure when I will get my period. From those who have experience with cycle changes, should I expect it in the normal 27 days or in the 40 some days? I'm already experiencing symptoms like breast pains, which makes me think I'll be getting it in the normal 27 days. Nothing like this has ever happened to me though, so I'm not really sure what I should look out for, or if I should be concerned. Thank you!