Wow! What kind of phone are you using, out of curiosity ? Strava on the phone will cut corners, literally run a straight line through a corner. I've switched to a Garmin, it's an older model (705) and weighs almost as much as the bike itself but it is dead accurate.
Garmins are cheap if you can pick one up used. And thanks for the follow on Strava, the next 5 weeks should have some choice words to describe my rides!