I’m confused, please help :-(

I have just recently starting working in a corporate job after graduating from university. It has never really occurred to me that I have bad social skills/or to the extent of being dumb, but from my current interactions with my coworkers, it feels like there’s something wrong with me. And I feel really suffocated as this has never really happened to me in the past.

In the past while I was still a student, I felt like I didn’t really have issues with social interactions. In fact I thought I was considered one of the more outstanding students in school (in academics, co-curricular etc), and have many friends/friendly with acquaintances. I was also a student leader in school, and could execute large things/events/plans well. However, I have to admit that I do suffer from some anxiety issues, I guess mainly due to a fear that I won’t do well in school. While I was never extremely confident, I was also not unconfident (not sure if this make sense). I was also never an “outcast” in school (at least that’s what I believe), in fact I was always one of those who would actively befriend students who are left out.

However, ever since I started working, everything changed, as though I became a different person. Let me just list down ridiculous things that I’ve done/faced so far at the workplace, as though I’m a different person.
– I find difficulties in keeping up with conversations, or having a totally different frequency from people that isn’t even logical. Then I’ll look back at the conversations and be thinking “wtf is wrong with me?!” or “why did I say that?!”
– Some colleagues seem to think that I’m dumb/cannot understand simple conversations, and would deliberately slow down to explain things to me. To that, I have once heard another coworker let out a snicker/laugh when it happened.
– I am really shy and reserved, and sometimes have no idea how to initiate/continue small talks (gosh how do I answer “how are you” and those “corporate talk” social conversations)
– I find it so difficult to laugh at others jokes, but this is probably because I have a high threshold for laugher? So I find it very awkward when others are laughing but I’m not, or even when I try to fake a laugh, it’s so obvious that it’s forced
– I find it difficult to string words, e.g. trying to explain something
– I seem to appear visibly uncomfortable at high energy large group events, I don’t seem to vibe that well and even claustrophobic?
– I always think a lot before replying in conversations, for fear that I will say something wrong/offensive
– Apparently coworkers first impression of me is that I’m extremely introverted/rigid
– (A lot of other examples that are hard to describe in words)

I am really confused what exactly is – is that social anxiety? Is the anything I can do to improve the situation or my social skills in general? This is extremely worrying and troubling for me as I work in a client-facing role. Any help will be appreciated, thank you so much.