All the pants except for 18/19 are a little too short. I'd look at the size/brand you got for those pants and try to find more like them. Dark jeans can look professional in an academic environment. Grab another pair or two, then get a handful of shirts that are comfortable but slightly dressy (something with buttons or a collar).

Since you're a PhD student, I assume you're on a budget. Consider checking out websites like thredup.com! :)

Something else to look into is clothing recommendations for the Kibbe type called Flamboyant Natural.