No, don't go for a ride with it really low. As Tommy1955 says, make small adjustments - and don't make another until you are certain whether you're going the right way or not. If you aren't using cleats, though, I think you'll struggle with getting the cadence up as your foot will tend to slide around on platforms. If you don't feel confident about switching to cleats you could try some old fashioned toe clips with straps.