For my son, I used a boppy. I didn't love it, it didn't fit my body type (I'm large), and I felt like it wasn't big enough for my son. I did need something though. It really helped me keep a consistently good latch, once his mouth grew enough to fit my large nipples.
I planned on getting this wonderful pillow, but just found out the company is no longer making them.
I don't recommend the Breast Friend for larger women because it straps on around your waist. I'm a size 16 and it barely fits around my waist. I use a Leach nursing pillow and LOVE it. Dh also uses it for giving dd bottles when I'm not home. You can see a pic of it if you click on Olivia in my sig. I think it's in the fifth pic. Don't worry, there are a variety of prints.
I love my Boppy! I have had the same one since ds was a baby and we still use it at almost 3 years old. I also use it with the twins. I like it better than my twin nursing pillow. It is nice and broken in.
I used a boppy for quite a while with dd. It didn't fit me well, and it always seemed like dd was rolling into the crack between me and it. Then I bought myself a buckwheat pillow, and found I didn't like it for sleeping, but tried it for nursing. It was great! It "molds" so I could squish it into the shape I needed.
When my dd was newborn, I tried the boppy and could not ever get it right. I ended up using just a regular bed pillow, folded under a little to provide extra height for her head. That was helpful until she could latch on really good on her own and now I don't use anything, although I do like to sit in the corner of the couch & lean on the armrest.
I used a boppy and had the same results you did. It didn't really fit and it got smashed down a lot and I was still slouching. I used a My BreastFriend pillow compliments of our local WIC BF support. I LOVED it. It was more firm fit better and was much easier to wipe clean withough havign to get right out and wash it. I still use the boppy for other things but the My BreastFriend was by far my Breast friend. Good Luck
I should add that I was a 14-16 while using the boppy as well as the My BreastFriend.
I used My BreastFriend and thought it was fine, but in the end I ended up not using a pillow at all. With the pillows their lower body (assuming you use the cradle hold) is up against your non-nursing breast. It is better to have it right up against your body, which is not possible with a pillow. Without one, you hold their body at an angle and the lower part is more under your breast. By holding them really close you can get better latch, I think. And you don't have to worry about strapping a pillow on when you have a hungry baby. But this is JMHO.
I don't like the velcro on the ends and keep thinking that I will cut it off, but haven't yet. Ellie is only a week and a half old....so there is still time. I am thinking about sewing up another one to keep in my bedroom for nursing.