How to stop being such a timid person?

Anonymous
I’m plus size and quiet, I’m not outgoing and have insecurity issues. At work I stay away from confrontation, I work with nurses and I’m afraid they think I’m easily able to be pushed around. I’m trying to get assertive, but I’m 26 and I’m not there yet. I’m a CNA, but sometimes the nurses can be bossy I try to ignore it but I want them to think that this isn’t okay. One nurse told me I’m quiet and don’t talk a lot, idc though cause I’m not telling personal details for them to gossip about. I am bad at socializing, I used to sit far away from them but now I’m sitting by them. They say I do a great job, but I feel like a kid. They are younger than me and are so smart and confident. I don't know what to do, how can I get more assertive?

They don’t believe me when I tell them I’d tell them if they were being rude, I don’t want them thinking I’m a pushover.

Even on video games I have a plus size character and I get shamed daily fat shamed. I know it’s VR but it’s like real life. Anyways, how can I end this? How can I make people think “oh she takes no shit”.

I’m 26 almost 27. I have gotten better but I want to be the best
How to stop being such a timid person?
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