"No, I did not expect this at this point in my life but everything happens for a reason!"
That's Brittany Matthews -- Patrick Mahomes' fiancee -- getting pretty candid about her pregnancy ... revealing the two weren't planning on having kids before their wedding, but they consider it “the biggest blessing [they’ll] ever have!”
Matthews -- a fitness pro who's been dating the K.C. Chiefs QB since high school -- says she was on vacation when she found out she was preggers ... and almost didn't realize it at first!