Swelling?

I know swelling is normal in pregnancy, especially 3rd trimester. I am 28 weeks and have started swelling so badly that I can only wear two pair of shoes and my feet hurt so badly. I know that you are supposed to keep your feet up, but I’m a teacher and this just isn’t possible throughout the day. Does anyone have any other suggestions for me? I have tried increasing my water intake, propping my feet up on the wall periodically for about 15 minutes, and wearing compression socks. (Problem with that is as a teacher I have to dress professionally and they don’t look good under dresses or in flats). I’m desperate for help since I just entered my third trimester and the thought of suffering through 12 more weeks makes me want to cry. 😭