Ages

I might be the only one that having trouble with this but I'm having trouble figuring out everyone's age in the books. First off I do know jacks supposed to be at least 28 in volume 4, Jerry is maybe 2 or so years older than jack so maybe 30, Rosa was said to be out of college age so maybe 24-25, and o brian mentioned being in the same age group so probably the same age as Jerry. That should be right but there are inconsistencies like riggins mentioned jack to be 26 and everyone referring to jack as a young man and can't think of 28 as a young man. Jerry probably is 30 but it was mentioned he left home in college so it's hard to believe he was just around with the cult for almost 10 years. Rosa is kind of mentioned to have a very sheltered like but never mentioned any college or other jobs prior. Amy kind of hard to tell since her interactions with riggins would suggest the were close in age, and he would have to be in his 40s to be Vanessa's uncle. Plus she is a chef now so I don't know if there is an age requirement.