Pumping exclusively (help)

I exclusively gave my son breast milk for 13 weeks when I all of the sudden noticed him not wanting to nurse anymore. (Mom mom and hubs would give him bottles while I was working and he'd nurse from me when I was home/off work/at night.) His feedings times on me kept getting less and less and he'd favor his bottle all of the time. Which was fine as long as he'd be getting my milk, I was fine with that. I miss our bonding time nursing but as long as he's still getting the good stuff I'm OK! Now that I'm constantly connected to my pump, I feel like my nipples are more achy and like mtrboobs are never completely empty!!!! Does anyone have a similar issue or know why that's happening or what's going on!? I know a babies sucking is stronger than the pump, but why the sudden achiness? I don't think I'm getting an infection... At least I hope not!