Hi there my friend, I'll try my best to answer your questions so here it goes:

Literally, the nose plug check doesn't work and I think I actually felt pain by pinching myself! I mean, seriously, what?
Ah yes, this is a very common case among us lucid dreamers. Anyways, In certain dreams, some reality checks won't work while others will. For example, the "plug-nose" method will work in dream X but will not work in dream Y. Instead, the "count your finger" method will work in dream Y but not in dream X. Or in other words, certain RCs won't work in certain dreams. I suggest you widen your knowledge or your arsenal of RCs. The more, the better. Some common RCs out there are turning of the light switch, passing your finger through your palm, looking away and looking back at your digital clock, etc. Try reading the Reality Check Article by Demerzel. It contains a handful of RCs.

Could I maybe move while dreaming, so I actually plugged my nose and pinched myself? Could I possibly have a sleep problem that makes me not enter SP?
I just want to clear one thing, you don't have any SP problems my friend. If you are able to sleep, dream at nights, and able to wake up during the morning. Then, you don't have any SP related disorders or flaws. But of course, you might have an SP problem if you often Sleep Walk at night. But as for you, that's less likely the case am I right?

...try to talk in dreams and find it incredibly hard...
Probably a dream quality/stabilization issue. Have you tried stabilizing your dream? Sometimes, the dream's quality affects the things you can do in a dream. So I suggest you try to improve your dream's quality by doing a dream stabilization. There are a lot of dream stabilization techniques out there like rubbing your 2 palms together or shouting "Increase dream quality". I know this is crazy, but try licking any bitter things in your dream or swallowing painful things. This might just activate your voice

Holy crap! I'm trembling!
Your dream was probably mimicking SP, or in other words, you've experienced what I call a "dream SP". An SP within a dream. I've experienced it before. But, take note that it will not take you to a dream inside a dream. It'll just teleport you to another dreamscape.

Did I miss something or do you need more clarifications? Feel free to ask and hope this helps