C., I had a similar situation with my 5 month old. I had to stop breastfeeding at around 5 weeks. It was a very difficult choice for me, but was necessary. I know what you mean about that. I still feel bad, but there was and is nothing I can do. Also, my son spits up often. No projectile vomiting or anything, just spitting up. I can almost never do tummy time because no matter how long it has been since he ate, he will always spit up when he rolls onto his tummy. I have seen three different peds, and they all say reflux. We don't do meds with him because he is gaining weight. I make sure to burp after two ounces and keep him upright after he eats for a while.
BTW, one ped told me to put cereal in his milk, so don't feel bad about that decision. I don't do it for my own reasons, so I don't know if it works, but she said it may help keep the milk down.
I will say that the spitting up has slacked off some as he is getting older, and as long as he keeps gaining weight and isn't fussy I don't plan to do anything different. I was very concerned at first because my older son did not spit up. However, he seems happy and healthy. I would say if your child is healthy and happy, just wait it out and see if the spitting up decreases.
Good luck.