In Cover 2 both safeties will be high and in cover 2 the weak spot is the middle of the field so a dig route, slant (if the WR gets past the MLB) are better routes to run. In Cover 3 there is usually only one high safety and there are generally soft spots in the cover 3 from about 8 yards past the line of scrimmage (over where the LBs are but in front of the CBs covering the deep part of the zone).
Bear in mind this year defensive play books have more plays where pre-snap, the defense appears to be in one kind of zone but is actually in another zone. If you are having problems with drops try some shorter patterns like curls or WR/HB screens to complete passes early and get the confidence up. 10 games still isn't a huge sample so I think the more you play the more you will recognize and be able to read defenses.