When Kitty Pryde was introduced in Uncanny X-Men 129, she was described as being 13 years old. In Uncanny X-Men 141, we are shown a grown up Katherine Pryde - specifically in the year 2013. We are not explicitly told her age, but she is visibly older - arguably 30 years older than her then-current 13 year old self.
Comics, in general, use a sliding time scale where time only really passes as necessary - or to make important relevant links to reality (e.g.: The Amazing Spider-Man #36). This, of course, creates some continuity issues (Archived link) although we have now caught up with the year of The Days Of Future Past, none of the characters depicted have visibly aged nearly as much as the story showed us.
In Earth-616, Kitty has grown up and graduated college (though being a genius means this probably happened at an accelerated rate). She has graduated from the X-Men, joined Excalibur and returned back to the X-Men (repeatedly). From the very beginning, there was a love interest between Kitty and Peter Rasputin (Colossus), but editors didn't approve of a 14 and 19 year old in a relationship (Archived link). They have since both grown up and consummated that relationship.
Despite there being a lot of attention being paid to her age early on, there does not seem to be many clues to Kitty's current age. Are there any other indications of how old Kitty is in Earth-616?