Joined: Mar 2011
Posts: 457
Likes: 0
From: Chapel Hill
Bikes: Canfield Yelli Screamy, Pivot Mach5, Specialized Roubaix, '65 Hercules, '79 Schwinn Stingray Lil Chic, '68 Schwinn Stingray Fastback, '89 Specialized Allez Epic, '86 Battaglin World Champion
Standover height is highly overrated -- you're not riding the bike with your feet flat on the ground, straddling the top-tube.
Sounds like you're in between sizes. If it feels comfortable while riding, then you're good. Might want to test ride a medium sized bike from one of your local shops because no one here can tell you if your bike is too big.