Can't get rid of "belly pooch" (lower abs)

Hello everybody.

I started working out with FB about four three years ago. In the past couple of months, I have finally purchased dumbbells and my body is visibly getting more toned. My main problematic area is the lower core, fondly known as "the pooch". While my upper core is fit and straight, the pooch is in the shape of a small mound.

I am a 25 y/o female, 55kg (121 lbs), 1.60m (5'2)z I work out regularly at least four times a week and I stay far away from fast and/or pre-packaged food. I used to be very skinny as young girl, but my form had filled very quickly. I don't know if it's relevant, but I will mention that i have a bellybutton ring.

I'm pretty sure I'm doing something wrong, bud I don't know what it might be.

Could someone please recommend a good way to get rid of the infamous "pooch"?

Much appreciated!