A.C.
I'm not a runner or exerciser LOL I am however a phlebotomist, regular blood donor and used to work for the red cross. So having said all that here's what I recommend for future blood donations.
1. Double up on your fluids for at least 48 hours after donation, so if you've doubled your normal intake of fluids for nursing ... double that. Getting extra fluids a couple of days before hand is a good idea also.
2. NO strenous activity for a minimum of 12 hours ... 24 is actually recommended. Basically take it easy for 24 full hours after donation.
3. DO NOT skip any meals for 24 to 48 hours after donation. Get lots of good complex carbohydrates and proteins. Since you're nusring especially, I'd add at least one or two extra snacks to your meal plan.
So if you give blood on a thursday afternoon I'd suggest waiting till saturday morning to resume running, as an example. Give on a thursday morning wait till friday evening. I personally always take advantage of giving blood and do the bare minimum for 24 hours :)
Anyway I hope that helps with future donations :) Let me know if I can answer any other questions about the process. I've been giving blood every 2 months (with some time off while kids were little) since I was 16 and did the job of collection tech.