How to avoid mastitis while engorged...

ns1

DD STTN last night for the first time in a loooong time!  Yay!  I'm hoping it will keep up and not be a fluke, but I'm trying not to get my hopes up.  

But...as a result of this STTN, I was super engorged this morning, and she only fed on one side, so until I pumped next at work, the other side (left) was pretty uncomfortable.  I tend to just feed and pump according to what LO needs.  I go by the my-body-will-adjust-to-her-needs-and-schedule motto and it's worked fine so far, so I don't really want to add unnecessary pumping sessions.  (Plus I already produce a little more than DD needs, so I don't need extra.)  

My concern is that I feel like the left side of my left breast is not draining fully!  It's tender to the touch and just feels a little more full than normal.  I really want to avoid clogged ducts and mastitis.  I'm trying to massage it when LO is nursing and when I pump, but it's still about the same.  Any other suggestions?