You all must not be doing many side quests or exploring at all - I always get to level 30 well before end of game, long before end of game. If there was no level cap, I'm sure I could hit level 40, possibly higher
There's no reason to explore a lot of times for me since enemies at southern half of the map are too easy and the northern half have few locations with enemies that pose a real challenge.
And there can be loooong stretches of nothing and once I actually find a place it might not be of much use anyway.
So exploring isn't something I do in New Vegas since it's really really awful IMO.
And I don't do every single sidequest on every character, I switch it up, sometimes I help FotA and sometimes I don't.