Plus size fashion for a teacher

I am a high school teacher size 3xl on top and bottom. Thus far my career fashion could be described as “what fits and is cheap” and I’m kinda tired of it. I have no idea what my style is as I grew up in Lane Bryant’s and Walmart.

I don’t have a lot of money so I’m still looking for cheaper clothes but my question is how can I look more put together on a budget? I work with teenagers and I think I get judged more harshly because of how frumpy I feel I dress.

I’d love some suggestions for how to accessorize or cheaper professional brands for plus sized women.

Thank you!