As stated above, you do not want to lower the bike more than 1 1/8".
I'm short at 5' 5", my inseam is about 28" and I've lower my bike .75 inch and have not had any problems. I can't flat foot, but can get both my toes on the ground.
I've learned to ride the bike on tippy toes and avoid potholes when stopped. If there was a indentation or something, get ready to shift your butt on the seat when stopped.
if you can't push the bike on flat foot while you are on it. learn to get off the bike when stopped and push the bike from one side into parking spot.
2008 Suzuki Vstrom DL650
2002 Ducati 998 Superbike
2001 BMW R1200C Phoenix/Independent
1982 BMW R100RT
1985 Yamaha FZ-750 - Sold
1982 Kawasaki GPZ-750 - Sold