Hi.
There are a few reasons why you might notice a stronger smell, but that doesn't necessarily indicate that there is a problem. The most probable cause is sweat glands. We have sweat glands in both the armpits and the pubic area. According to Dr. Karen Rosewater, the strong scents associated with these regions of the body grow more pronounced once a person reaches puberty. Maybe this is why you're just beginning to notice it.
That's probably the case since you seem to have proper hygiene and don't have a discharge. Dr. Rosewater suggests wearing cotton panties--or panties with cotton crotches--to help the area "breathe," thus cutting down on the smell.
If you're still concerned, though, I would recommend asking your mother to take you to a gynecologist. Be brave. Just because it's your crotch doesn't mean it's "dirty" or something to be ashamed of. If something weird was happening inside your ear, would you hesitate to go to the doctor? Probably not. Just think of it as simply another part of your body you want to keep in tip-top shape!