Breastfeeding/pumping working moms

So I work a 12-13 hour shift scheduled from 6am to 6pm 3 days a week. On the days that I work I get up at 430am feed baby, get ready for the day then pump at about 5am. I then get to work and am able to pump between 8-830am, then I go to lunch about 12 and breastfeed my son, then I am able to pump again at work between 3-330pm. I then get off work roughly at 630pm and go home and breastfeed my son again and then pump again around 8pm before bed. On the days that I don't work I usually pump after the morning feed and sometimes before bed but not in between. I guess my question is should I be pumping at the same times everyday even on the days that I am not at work? I exclusively breastfeed when I am home with a morning pumping session and occasionally others. I am just worried about not being able to pump enough while I am at work. I have been able to get roughly 16-20oz on the 4 pumping sessions that I do on my work days which has been enough for the next day since my son is 10 weeks old and is taking 3oz bottles but I am worried about my supply as he gets older. And help would be appreciated.