Late period confusion

Usually my period it comes on the 8th of every month. Last month it came on the 7th and the 7th of this month nothing. Me and my husband have been trying to conceive for 3 1/2 years now and have been unsuccessful. I just wanted to know what are some opinions on what the ladies on here think is going on? I have done ovalation calculators and the said that I should be able to take the test today or either have my period. I'm so afraid of the disappointment the comes in finding that it's another failed attempt. PLEASE HELP!!