Breastfeeding Difficulties

Briana • Wasn`t expecting that!
Help! I am having a hard time with breastfeeding and I'm starting to lose hope. Let's start from the beginning.. Baby is almost 3 weeks old, in the first week we were having a hard time getting latched on correctly to my left breast and I was in pain during every nursing session. She would knaw on my nipple with force and eventually broke the skin causing a major cut and I couldn't feed her on that side. I fed from the opposite and pumped on the injured side. A couple of days later I got mastitis. NOT FUN! I was on antibiotics and the infection cleared and my it healed. 
Now for my current situation... My left breast (the one I had all the issues with) is now softer than ever and never gets full of milk where as my right breast (the one she had been actively nursing from) is now over producing, leaking a ton, and very uncomfortable. My breasts are now lop sided and the lactation consultant at the hospital I delivered at says to feed from the underproducing breast for 15-20 mins and then switch to the over producing breast for 5 mins to relieve pressure and get comfortable then finish in the opposite side. This is supposed to even out my supply.  
I feel like my baby isn't getting enough to eat with this system. Has anyone ever experienced this type of situation? What did you do? I'm desperate for any advice.