Eric, you sound serious to help yourself, so please take the following criticism constructively. You are using o2 incorrectly and that is why you are not as successful as you could be and hopefully will be.
You truly need a NON-rebreather mask. Order it from the ch.com store-yellow tab on your left side of the screen, ships within 2 days, it's worth it's weight in gold. With all due respect your rig from 14 years ago is quite impressive, however just not able to compete with a NRB mask with 3 litre bag and 6 ft hose.
Stop holding in your breath, you refer to it as a "hit", and exhaling, then repeating. You must hyperventilate as fast as you can for as long as you can. It is tough work, but it is the optimal abort method. The concept is to rid the co2 buildup which is the culprit causing inflammation of your trigeminal nerve which creates your pain. Breathe in the o2, breathe out the co2, as deeply as you can inhale, as deeply as you can exhale, as fast as you can, as if you just ran a marathon, as if you are a panting dog in heat, as if you are having an asthma attack, i'm serious, this is truly the fastest and most effective method. The NON-rebreather mask (with 3 litre bag attached) you will order called an Optimask is designed for this type of hyperventilation. Don't be alarmed when feeling lightheaded and coughing, this is a common side effect, along with a tingly sensation at your mouth and fingertips.
Good you have welders o2, then you have no prescription challenges of getting as much as you need whenever you want.
Good you have a welders regulator because the high flow rates are required to hyperventilate. Welders regulators do not have lpm (litres per minute) but don;t be concerned of that, welders regulators will provide a higher flow rate than you can compete with.
Giving up after "15 hits" or so is a major problem. Remember you are no longer taking hits, you are hyperventilating/breathing as fast as you can, as deeply as you can, inhale as deep as you can, then exhale as deep as you can til the wind is knocked out of your stomach. Plenty of o2 "how to" threads available on this site...yellow tab on left. Many can abort an attack with o2 after 5 minutes of effort. then to avoid a repeat attack and/or rid the potential of a quick co2 buildup...lower the flow rate and breathe normal for an additional 5 or 10 minutes after the abort. Then live life large between the attacks!

Sitting upright, excellent to read. Standing and sitting upright are preferred posture during o2 therapy because your lungs are wide open which provides you to maximize your breathing. On the contrary, laying down and using o2 is counter productive as your lungs are somewhat obstructed in this laying position. So always hyperventilate standing or sitting upright.
Excellent you recognize the priceless value that you must get on the o2 at onset of attack, the sooner the better. If you wake up with pain, you are already lacking time and need to move quickly to get that mask to your face and begin hyperventilating. If you can not get to the o2 before you reach a KIP 5, chances are you will have serious challenges aborting with o2 on that particular attack/attempt of o2 therapy. The sooner the better!
Do you have a headache doctor from 14 years ago? Where in Central NY do you live? I'm going to research NY for you and provide you a list of recommended doctors. You truly need preventative treatment, as abortive treatments are only the quick fix. The goal of preventative meds is to reduce the frequency of attacks, minimize the intensity of the attacks and shorten the cycle. Not all preventatives work. What worked for somebody last cycle, may not work this cycle, as the beast morphs, it is all trial/error, but you must be knowledgeable moreso than your doctor so you are not prescribed a med and/or a dosage that is known to be worthless.
As for your bulging eye...I personally have never heard of this specific side effect of a CH attack, however you should get it checked out if it continues to concern you. Hopefully others from this board will chime in with their thoughts of this swelling/bulging eye issue.
Below is a long list of recommended doctors in New York who are familiar with CH's, updated 5-20-2012 from the OUCH website. Hope this list helps you get into see somebody quickly for preventative treatment.
-Gregg in Las Vegas
"
[u]New York[/u]
Bay Shore:Dr. Norman L. Pflaster South Shore Neurologic Associates
Bronx:Dr. Randall G. Berliner Regional Neurological Associates
Dr. Seymour Solomon Montefiore Medical Center
Dr. Derek G. Randall
Camillus:Dr. Kevin W Thomas FamilyCare Medical Group – Neurological Division
Canandaigua:Dr. Robert S. Knapp Ontario Neurology Associates
Cedarhurst:Dr. David Steiner Five Towns Neurology
New York:Dr. Mark W. Green␣ Mount Sinai Center for Headache and Pain Medicine
Dr. Alexander Mauskop New York Headache Center
Dr. Lawrence C. Newman The Headache Institute St. Luke's Hospital
Owego:Dr. Keith Nichols (PCP)
Rochester:Dr. Gilbert Proper Pain Symptom Management Center␣
Dr. Joseph I. Mann
Greater Rochester Neurological
Schenectady:Dr. Bruno P. Tolge Schenectady Neurological Consultants and the Headache Center of Northeastern NY␣
Stony Brook:Dr. Patrick E. Poole
White Plains:Dr. Ronald M. Silverman Neurologic Consultants of Westchester
Williamsville:Dr. Peter R. Kinkel Kinkel Neurologic Center"