One boob always feels fuller?

Spec
I'm EBF my 3 week old and I'm very careful to always alternate breasts. 
But I feel like my right one is always more full. 
I fed my baby from my right just over an hour ago and it is already full. The next feed I'm due to use my left, but it's quite soft. 
I'm tempted to use the right to relieve pressure, but won't that signal to my body it needs to produce even more?
Who knew this breastfeeding business was so confusing!