Don't attach too much importance to the daily AHI index when it is =<5 since anything in that area is in the green zone. Daily checking the AHI tends to be counterproductive, akin to checking the clock every time you wake up. Striving for a zero is foolish and produces needless obsession and stress that can interfere with your therapy.
A weekly check of the SD card is soon enough and makes for a better interpretation of any trends. As far as the clock goes, get it out of sight.
ps. The initial goal of PAP therapy need not be to get a long night's sleep. It can be to get sleep that isn't damaging to your body. That may well come in shorter sessions than you like but that's because the equipment and regimen takes a long time to get adjusted to. The longer sessions will come with time so stay the course. Get an afternoon nap when possible to speed acceptance along while getting you some added sleep time.