The tubes can come unsutured and a path can be created that is large enough for a sperm to travel in. However, it is rare for that to happen. And the thing is, you are relating things that aren't really related in anatomy. The cervix is the lower end of the uterus, and the ovaries and tubes are snugly up and away, in the abdomen. It is true that there is fluid in the tubes that moves downward, so the egg can travel into the uterus; possibly some of that fluid does make its way all the way down and out of the uterus and its absence might be noticeable after the tubes were tied. But that isn't cervical mucus, it's fluid that comes down from the tubes. Usually cervical mucus responds to other signals and thickens or thins based on your hormones (and probably your nutrition and other factors). Also, a period is not affected by the tubes being tied, it's the same endometrium as ever.
What I suggest you do is take a home pregnancy test sort of randomly (pick up a handful at the Dollar Store, they are cheap and surprisingly good) throughout the month. Take one when you are cramping up, and take one just because. If no pregnancy-test positive, no pregnancy.
The other thing that might be making your periods unpleasant is a fibroid.
Thanks so much for your comment. That is a great idea. I am going to try it out. I did take another one because I was late this month. It came up pos then had the awful period three days later. I understand now about the cervical mucus and it does make sense. I know where everything is located... maybe just having a mommy moment LOL
With the mucus I did notice a drastic change after the first few months of having my tubes tied, there is a lot less. This past month I have noticed the increase in volume now that I am fixing to ovulate. It was to a point that it shocked me that I had that much. Hopefully I can figure out what is going on, but if my period next month is anything like it was the other two months I am going to see a Dr. It was almost as bad as labor pains.