I pump once and it throws things off !

Hi all ! I need some help! I have an over production and an overactive letdown. I guess it’s not the worst to have this issue but it’s so stressful . My baby suffered from it due to the foremilk imbalance and the overactive letdown. So I started block feeding which has helped a lot ! But then he slept a few nights a lot longer than we were used to and I had a clogged duct, i worked that out and it resolved but since he was sleeping longer I had to pump once in the morning hit i swear every time I pump my milk goes out of wack and low my breast feel so full and I feel a clog forming . I have to go back to work and plan on seeing my son on my lunch breaks to nurse . How do I pump at work for his meals , nurse him on my lunch and then when I get home without having way toomuch milk ?? I don’t know what to do . And when i have more milk I have an abundance of foremilk which he gets full on and then gassy :/ heeeelp