Hi there
Sometimes the follicle (cyst) that contains the egg doesn't release so you don't ovulate and the cyst gets a little bigger and then vanishes. We call them functional cysts and are normal, but they can delay your period and give pregnancy symptoms. Stressing about missing your period may then delay it even further.
If you still don't have a period after a month then maybe you should chat to your gynae. They can give meds to sort the cyst out if it is a cyst. If you continue to have longer cycles which are not the norm for you then you may want to have a check up too.
If you are ttc the sheer stress of it and doing tests etc can disrupt your cycle.
Good luck.