I quite often have a scary choking feeling when just about to nod off to sleep.?

GERD. You can modify the diet, sleep on two + pillows, thicken feeds, avoid those foods that make you burp, take antacids even ppis or h2 blockers and/or see a GI specialist to r/o gastro-esophageal reflux disease (gerd) p.S. How's your weight, post pregnancy?
Gasping for air? Are you short of breath or gasping for air too? Do you have excessive daytime sleepiness? Gerd, along with these others are symptoms of sleep apnea. If you have more than one of these you should see a sleep physician. If only the gerd, see a gastroenterologist.