Heya;
Honestly, I suggest just dropping your class (if you can afford it) and get private lessons (pool sessions, and open water). You can do your open water dives AT ANY TIME once you complete your pool sessions, just get the staff members your getting you lessons at to fill you out a waver, and tell them you want to do your open dives later. I would never have dreamed of doing public lessons... nevermind with 15 people. You say you're socially awkward, well I'm a little on the shy side myself. I don't think my mind would be able to function well with 15 people jammed near me going thru the same course I was. That would make it hard to concentrate for a non-shy type, nevermind someone who's shy. Even if you haven't made these distinctions consciously in class, try private lessons, with unrushed, competent instructors, with no-one in the class but you... it would seem like a completely different world, and it would be a completely different experience.
I mean, heck, depending on the instructors, PRIVATE classes can suck! So, I can only imagine how bad public ones can be, with nice, yet crappy/incompetent instructors.
My poor mother had nice, yet crappy/incompetent instructors, a husband and wife duo; their methodology was horrible for my mother; they rushed her thru the class without even giving snorkeling portion of the lessons first, till she choked, and gagged enough, and they finally woked up to the prospect that she needed that portion of the class just as much as the diving part... they continued to rush her, and my mom's one of these types who thinks she's 20 at 67, and the instructors rushing her, inadvertently caused her knee to get injured, when performing an underwater maneuver, in a manner like they did. From the way my mom described, her class sounded just like yours.
So if you feel rushed, drop the class like a rock (if you can afford it, heck lessons are only about $200, and you only have to do them once) and find a class/instructors you're comfortable with. Heck, I had an instructor wouldn't shut up about how horrible depth gauges were, and kept trying to make it out like computers were so superior, and she even tried guilt tripping tactics to get me to buy a computer, saying about how a computer user would have to leave earlier before their bottom time was up blah blah blah. this went on for about 20 minutes; and we were supposed to be in the water those 20 minutes ago. *shrug* I just got up from the chair, got my gear, and walked out. I had better things to do.
I was going to use a computer during class, and she knew it, she just wouldn't shut up with the sales tactics.
a couple of days later I found an instructor who was a MILLION times better than any I had yet. He was quiet, mild mannered, didn't rush whatsoever, and everything went perfect, no sales BS, ETC. Just shop around (if you can afford it) But at any rate, definitely try to find unrushed, private lessons; it's just plain well worth it!
P.S. Unfortunately, yes, you can injure your lungs, in so much as ascending less than a foot underwater if you hold your breath. Just make a conscious effort to always breathe, no matter what while scuba diving, and never hold your breath.