Hey Nadas looking good brother.
Regarding the Ab/Kidney side gap, according to the CRL there is no measurement requirement at basic however, please check with your garrison's GML as to what they require. The following is all that is required for basic Ab to Kidney. That said L2 and L3 will have tighter requirements.
Abdomen Armor
The abdomen armor has a button area that matches the color pattern shown (3 blue + 6 gray); buttons are approximately 7/16" (11mm) in diameter.
Besides filling in the thigh gaps front (as suggested by Aizenoso) do the same for the rear or trim for mobility. I also suggest you remove any return edge that may help the armor sections sit closer to your body.