OP, you need to do what you feel comfortable with, but I'll share my experience:I BF my first child and she was horribly fussy from the moment we were home from the hospital. She wouldn't nurse, cried at every feeding, developed eczema, and even had blood in her stool. This was 14 years ago, so food allergies weren't as common as they are today. I called the dr and they suggested that I cut dairy and soy out of my diet. Because I could no longer have things like butter on my toast, I was eating more peanut butter than usual. DD just kept getting worse and worse - fussier and fussier. We were all miserable. Out of desperation, I put her on formula and in less than 24 hrs I had a totally different baby. She was happy, smiling, and happy to drink a bottle.
Fast forward 3 years to when I gave her peanut butter for the first time. She threw up, broke out into head to toe hives, and her eyes swelled shut. We got an Rx for the Epi Pen the next day. In hindsight, I believe that she was so fussy as a newborn because of the peanut butter in my diet. Since it started pretty much at birth though, I feel that she was born with the allergy. I don't think that I caused it by eating peanut butter.
Two years later, my next baby was born. DD hadn't been diagnosed with her allergy yet, so I happily ate my peanut butter sandwiches every day while I nursed the baby. He was BF for 6+ months with no problems whatsoever. He is 12 now and although he doesn't like peanut butter, he is not allergic to it.
By the time I had my 3rd baby, my oldest had been diagnosed and I opted to not have any peanut butter while nursing the baby. He ended up with a milk allergy and I eventually switched him to Nutramigen. He is 6 now and is no longer allergic to milk. Like his brother, he does not like peanut butter but is not allergic to it.
So I guess this is my long-winded way of saying that I think my DD's allergy was present at birth. She was going to be allergic no matter what I ate or didn't eat.
And my second child is not allergic, even though I ate lots of peanut butter when nursing him.