i have notice that a few people in my breed [ large] are still mating their girls at 18 months old, i thought that with the new regulations all girls had to be over 2 yrs old before pups can be registered , or is the regulations just for ac breeders

I think it depends what the breed clubs have agreed with the KC. I'm pretty sure it's 2 for my breed.

Yes the tighter rules only apply to accredited breeders the rest can do as they please as long as they don't contravene the universal rules, that is register more than 4 litters, mate a bitch under a year, have one whelp over 8 without prior permission, ditto more than two C sections.