What Do You Recommend to Gain Fullness in my Breasts?

You need both a breast lift and a small augmentation. Based on the footprint of your breast, I don't think a large implant would look good on you. I would favor a vertical breast lift with a very small amount of reduction on both sides (right more than left), and a small sub-muscular implant. You don't need a big lift, just enough to get the nipple centered over the implant foot print.

If you just go with implants, you may still be left with sagginess to your breasts.  The scarring for your lift will most likely go around the areolae and straight down, aka vertical mastopexy.  Since you don't want to be too big, both procedures may be able to be done simultaneously...it's difficult to tell you exactly yes or no without examining you.  Also, since you have a history of hypertrophic scarring, you'll need to keep this in mind after any further procedures and understand that this is a risk you'll be taking (ie getting more hypertrophic scars.)