You need to open up more from the BU and CO positions. Also don't be afraid to defend you blinds. With less seats the blinds come around more often and there are overall less players, so odds are that most of the time players will not have a hand to stand up to you. Play aggressive and really know your opponents. A loose table allows you to set mine and limp with suited connectors more often. If the table is tight you can't do this as much because the implied odds aren't there.

You also need to focus more on post flop play with players generally playing looser than full ring.

Personally I love 6max because there is more action, but this can mean you see more swings. Since I play for fun this suites my preference more, but it sounds like you don't have a choice from your OP.