discouraged and tired - do these numbers make sense to you?

I've been at this a year almost and still feel tired. My logged sleep hours are irratic and I'm not sure what to do or even ask at my appointment next week with the sleep doc. I think I need another titration. I can't seem to fall asleep without taking 1/2 Ambien. Some nights I sleep great, others (like last night) for only 5 hours. I expect to sleep well tonight since I didn't last night.
I try to be 'connected' & lights out by 11. Last night I threw in the towel at 1 and took the Ambien. I walk around dizzy most of the time and it's not my blood pressure.
My numbers on my ResMed S8 VPAP Auto from last night are:
Device Settings
Therapy mode: VAuto Pressure Support: 3.0 cmH2O Min EPAP: 5.0 cmH2O Max IPAP: 15 cmH2O
Pressure - cmH2O
Median: 7.0 95th Percentile: 8.6 Maximum: 9.2
Calculated Pressure - cmH2O
95th PC IPAP: 10.1 95th PC EPAP: 7.1
Leak - L/min
Median 0.0 95th Percentile: 18.0 Maximum: 22.8
Tidal Volume - ml
Median: 320 95th Percentile: 900 Maximum: 1380
Minute Ventilation - L/min
Median: 4.6 95th Percentile: 9.0 Maximum 13.3
Respiratory rate - breaths/min
Median: 13 95th Percentile: 16 Maximum 19
AHI & AI - events/hr
Apnea Index: 4.6 AHI: 11.8 % Time in Apnea: 1.6
Hypopnea index: 7.2

As I was trying to convince myself to fall asleep last night, I would 'fall' then jerk awake and remember to breath. This happened many, many times. That's when I took the ambien. I find myself crying because this therapy isn't working for me - not because of depression but because I'm sad. I'm trying SO HARD. I've been 100% compliant and still feel like cr@p.
I don't know how to proceed.

your AI... is a little high. Wonder if it might be good to bump up your EPAP so that it's closer to the 7, 5 seems a little low.

I've found Ambien to be something of a two-edged pill, so to speak. Very, very effective but unless you have the non-generic and thus far more expensive time release capsules, the effect only lasts three to four hours. For those who have the kind of sleep inertia that keeps them asleep once they fall asleep, that short-term effect makes no difference; but if I take Ambien for a few days, I find myself waking up in the middle of the night and unable to go back to sleep. The main problem with the drug, for me at least, is that if I take a full dose of Ambien even once, I simply can't fall asleep the next night without it. Tapering off, with a half-dose for one night then a quarter dose for the next night before I discontinue entirely, has proved more successful for me, but I still won't sleep soundly until I've been off of it for several days.

And I agree that you should try bumping up your low setting a little at a time to see if that improves your sleep quality. If you're not getting enough physical exercise during the day, that can impact sleep. Finally, I have a rather odd suggestion: try saying "ka, ka, ka, ka, ka; and ga, ga, ga, ga, ga;" and switching between them as fast as you can for a few minutes several times a day. This simple trick conditions my tongue and mouth in a way that reduces mouth-leaks and improves my AHI.

I've been taking 1/2 Ambien for over a month now. Any suggestions to wean myself off of it or is it just cold turkey? Would Benadryl work? I've NEVER had a full night's sleep since starting therapy.
I'm not getting enough physical exercise, true. Your suggestion about the syllables is good; while I can finally breathe through both nares after nasal rinsing, I still feel like I have drainage on my palate & recognize the feeling as the place that collapses. Weight loss is slow, especially since I'm tired & seeking 'comfort' food. Thanks much for your responses - I do appreciate your interest.

Try a quarter dose for two days then cold turkey. The stuff is so strong you may find a quarter dose knocks you out as well as a half dose. If you can, go for a long walk or two the day you plan on stopping Ambien.