Lower ab workouts that you have seen resuls from?

I’m 17, male, 145 lbs, I’ve been lifting for 5 months and I’m getting muscular, now I really want abs. Since my metabolism is so high I already have pretty toned abs, but just the higher 6, I could have an 8 pack if I could get the bottom abs to come in but literally nothing is working. All the “lower ab” workouts I have tried just work the upper abs and I feel nothing in the lower ab section. So please tell me the lower ab workouts that you do that you have actually seen results with. Thank ya!