So frustrating!!

I don't understand! My period was 2 weeks late last month... Now my period was due on the 18th and nothing...I tested and it was a bfn...I am so frustrated! I was having fertile cm for a week straight & really thought i was lucky!!! But now no period & bfn!!!!!! Anyone experience this? I make a joke and say I hit puberty late too bc I'm 28 and now my boobs are starting to grow but not hurting...and bfn! Ugh!