Showdown % should be at least 25%, otherwise you are either being too nitty or taking marginal hands too far when you should have folded on the turn. Make a decision on the turn whether you feel confident with your hand and decide to get out or really stay in. Sticking around for the turn only to fold river is a HUGE leak as Turn bets are much bigger than bets on the flop because the pot has grown.

I wouldn't worry too much about your aggression factor.

I think if you continue success for another 10K at 25nl, try moving up to 50NL.