Back to work tips...

So I have to return to work in a few weeks 😓 and am trying to prepare so babe will have enough milk when I’m gone. I work long hours and will be gone about 11 hours per day. I have a spectra pump and can usually get 4 to 5 oz per pumping session. Baby takes both breast and bottle. How frequently do I need to pump to keep my supply up? Also does anyone pump in the car (I have a long commute)? What do I need to bring to work with me besides my pump and pump parts? Where do you store your pumped milk during the day? I have a lot of anxiety about leaving my boy and the pumping issue is causing me more anxiety... I have a busy demanding job so hoping I can find the time and space to make this work.