When I was 16, I was 225 lbs or so on a 6’1" frame. I was in decent shape, and worked out for football, but still had a “beer” gut.
… I got some water in my throat or something … but I was able to cough it up on my own.
I actually crawled along the bottom to the wall of the pool, and then stood up from there … no one dragged me out. Just coughed my head off for a few minutes 
Let me guess- you jumped in. When you jumped, you probably exhaled- maybe from the shock of cold water? Or were you ducked- also causing you to exhale before you hit the bottom?
If your lungs aren’t full of air, you probably won’t float. That’s why learning how to breathe properly is such a big part of it. Your lungs, when full, are like a life preserver inside your chest. You know how beachballs and balloons float? That’s what your lungs will do for you if you use them correctly. You certainly can sink, especially if your lungs aren’t full and if you are vertical in the water, but if you breathe deeply and calmly and spread yourself out, you can float.
anyone afraid of going under water, DO NOT READ THIS>>>>>>>
A classmate of my little sister drowned at a pre-graduation picnic- no alcohol involved- because he jumped off a dock to retrieve his glasses from a pond. The water was only maybe 10 feet deep, but the bottom was mud. He stayed down too long, exhaling all of his air, and then wasn’t able to push off the bottom (his feet sank in the mud). He was only an average swimmer, and as such didn’t have the arm strength to get to the surface without lung buoyancy or a push. It took them a long time to find him, and it haunts me. As I said upthread, I love being under water, but that incident made me much more aware of how to float.
Didn’t jump in – as a non-swimmer, that was out of the question.
I was on an inner tube, and someone else accidentally tipped it over. That’s essentially a dunking (you typed “ducked” for “dunked”, correct?)
Heh. So that’s the deal – human bodies don’t really float, after all?
I meant to type “ducked” as in “you were given a ducking” but “dunked” means the same thing, just different slang. My point was, you were shocked into exhaling, and the force of falling off the the float carried you to the bottom. Without air in the lungs, there was no reason for you to bob up, and you were understandably scared, so you tensed up and got trapped by the water.
Well, a balloon won’t necessarily float, either if it’s flat! Humans float because of fat content and air in the lungs (maybe a few other things, but those are the big two.) The air is what will make you bob up, but the fat will keep you up with minimal effort. So, yeah- people who can float/swim easily can overstate the effortlessness of floating. If you aren’t able (for whatever reason) to grab a gulp of air and hold it until you resurface, you may well sink- which is terrifying - as you know! I would imagine that ralph’s training featured “taking a breath” pretty heavily- suck it in before you hit the water and don’t let go until you can take another- if this is instinctual, it becomes hard to see how anyone can’t do it.
I had the water accident event when I was a kid and have never learned to swim. But, I have spent many hours snorkeling. With flippers I can move. Without them my feet make foam and no propulsion.
To the OP: After you’ve finished your classes, find some time to practice. Off-peak times when a pool has lanes open for lap swimmers is best (try Sat. or Sun. afternoons). Swim a few laps, rest a bit in between each of 'em if you need to. You’ll quickly know what you need to work on, and if it is something you do not think practice will fix, you’ll be able to tell your next instructor where you’d like help.
And don’t be intimidated if you end up sharing a lane with a speed demon. There’s no danger, and those are just the sort of swimmers who’ll love to help if you ask their opinion on your swimming.
Aww. Go ahead and check with the Y. I used to teach lessons at a Y – both children and adults – and the adult classes were much more enjoyable for me. The adults had many more misconceptions and bad habits to correct, but they actually listened and wanted to improve. There were just as many afraid of the water as in the kids’ classes, but in the kids’ classes I had to stop other kids from teasing about it. All the adults were very supportive of each other trying to learn.
Plus, they had better control over their body, and didn’t nail me in the 'nads when I was trying to teach them how to kick.
That is, approximately, the correct head position for competitive backstroke. 'Cept you don’t want your eyes underwater all the time, then.
The problem people have with floating aback or doing the backstroke is that they let their legs and hips drag them down – some almost seem to want to “sit down” into the water. And then, they sink. The further back your head is tilted, the more it corrects that problem. I used to remind my students “chin up, bellybutton up” which corrected the sinking problems.