When Billy first becomes manager, one of the players mentions that he's "still 6 years away from getting into an R-rated movie." This would make Billy 12 years old. Later, Billy's mom admits that she hasn't been on a date in 14 years, the last time she went out with her husband. So if she hasn't been with her husband in 14 years, who's Billy's father?
Actually, getting into an R rated movie only requires an age of 17. So 6 years away would mean that Billy is 11 years old.
Not to mention the fact that, "hasn't been on a date in 14 years" could very easily mean that, even when she was married, she hasn't been on a date in that long. I know that a "Date" with my wife can take a long time. Especially with 5 kids.
Besides, I wouldn't be so certain that 14 years is an exact number. It could have been something pulled from her proverbial ass.
Why would she be a slut? For one date? She was talking about when she met her husband 14 years before. (Remember Billy is 11). After they were married, it is more like "going out" than "dating".
Lou referred to a "date" as dinner with someone you do not know very well, so she said that the last real date she had been on was with her husband 14 years ago. This means that she was with him for a while before they had Billy. You are reading too much into it. The whole thing is very simple if you just listen to the words they use.
Some people don't consider doing things as a couple as "dating" once they're married. I know a lot of married couples who go out to dinner or go see a movie, but don't consider it a date because they're married. Woo...they waited a couple of years to have a kid--I know a couple who waited 14 to have kids so that they could do a lot of things they knew they wouldn't get to do after they had kids.