"Everyone else got under the water and I couldn't figure out how. I was hitting the button but wasn't sinking."
You are not the first person to experience that.
"After that my mask filled up."
You are not the first person to experience that.
"I was still struggling just to control my buoyancy."
You are not the first person to experience that.
"I was having issues with my hamstrings. I've never had a hamstring cramp in my life [...]
he said in all his years he's never had anyone cramp in both legs at the same time"
That is uncommon, but I have had it twice.
"my feet were starting to hurt because my boots and fins"
That should not happen. They're too small.
"It also kept fogging when there was no water in it"
Yeah, that sucks. You will get used to it.
"he told me it was okay and that it took him several tries to get his certification as well."
Nice.
"Anything under water I was just scared at this point. I couldn't get back under and I couldn't get my breathing under control."
Not fun
There is however nothing wrong with you. These problems are common. You just happened to experience ALL of them at the same time. I can understand why diving might feel a bit scary now!
"I probably need a proper fitting wet suit"
Skip the suit and fins for now. You need to spend some relaxing time at the shallow end of the pool wearing swimming trunks only. I've done it a lot and it's great.
You are not the first person to experience that.
"After that my mask filled up."
You are not the first person to experience that.
"I was still struggling just to control my buoyancy."
You are not the first person to experience that.
"I was having issues with my hamstrings. I've never had a hamstring cramp in my life [...]
he said in all his years he's never had anyone cramp in both legs at the same time"
That is uncommon, but I have had it twice.
"my feet were starting to hurt because my boots and fins"
That should not happen. They're too small.
"It also kept fogging when there was no water in it"
Yeah, that sucks. You will get used to it.
"he told me it was okay and that it took him several tries to get his certification as well."
Nice.
"Anything under water I was just scared at this point. I couldn't get back under and I couldn't get my breathing under control."
Not fun
There is however nothing wrong with you. These problems are common. You just happened to experience ALL of them at the same time. I can understand why diving might feel a bit scary now!
"I probably need a proper fitting wet suit"
Skip the suit and fins for now. You need to spend some relaxing time at the shallow end of the pool wearing swimming trunks only. I've done it a lot and it's great.