I have had GERD (gastro esophageal reflux disease) since I was about your age, Ritz. I have to take Prilosec prescription strength twice a day and it barely controls it. I do get a gurgling sound occasionally, but it sounds like your is much worse.
My advise is: Get thee to a GI doctor. It may be that the sound you are hearing (and probably feeling) is your stomach contents rumbling around in your upper esophagus. You stomach lining is equipped to deal with the high acid content of your stomach. Your esophagus is NOT! That acid can cause significant damage, including irritation (esophagitis), ulcerations, scarring that eventually makes the opening smaller and allows food to get stuck, a pre-cancerous condition called Barrett's esophagitis, and esophageal cancer. On to your lungs. They REALLY aren't designed to take stomach acid, but with severe GERD you can get reflux into your trachea (windpipe). This can trigger asthma, among other things. I'm surprised that your pulmonary doc didn't send you to a GI doc himself.
My Dad had untreated GERD for years and had to have scar tissue removed from his esophagus twice because food was stuck, and almost died when he got an ulcer on his vocal cords which caused his trachea to spasm and a severe asthma attack (he didn't know he had asthma). I've had my esophagus stretched twice because of scarring and have chronic esophagitis. My daughter is having an endoscopy, pH probe and esophageal motility test next week because she has eosinophilic esophagitis, esophageal spasms and slow GI emptying.
GERD is sometimes caused by a hiatal hernia, which can be seen on a barium swallow. Reflux will sometimes show up on that test as well. Hiatal hernia's can be fixed with laproscopic surgery. Lupus can also affect your esophagus and mess with the way the muscles contract to move food down and keep it in the stomach where it belongs. My rheumatologist says my GERD is from lupus.
Raising the head of your bed can help at night, because gravity gives your esophagus a hand in keeping the acid down. That's probably why sitting in a certain position helps with the gurgling. We put cinder blocks on their side under the feet at the head of my daughter's bed and it makes a big difference for her. You can also buy special blocks at Bed Bath and Beyond that are designed to raise beds for storage underneath, but you can just use two for the head. Avoid eating close to bedtime. Caffeine, soda, chocolate and acidic foods can make GERD worse. Pepcid is another drug that helps control acid that is available OTC (over the counter). You should check with your doctor before adding new meds, though.
Whew, that was probably TMI. Maybe there are a few tidbits in there that might help, though.