stress and irregular periods

Last August and now, just this past week, I was 4-5 days late with my period. All other times, I have been normal. Blood tests reveal nothing. In August, I thought I may have miscarried. There were more clots thean usual. This time too. But, my husband had a vasectomy. Never went back to make sure it took, but had a severe infection. I have been stressed ,but, I have been stressed worse than this and had normal periods. Can stress affect your periods this bad or might there be something else. I also have felt pregnant at these two particular times. I am 37. Part of me wants to be pregnant again and the other part says "no way! I'm too old" Remember....blood work keeps coming back normal. Thanks everyone.