birchykel - please don't feel that you are alone in going through this, there is support out there! I think lots of reflux mums find most GPs totally useless, you just have to persevere and not let them fob you off. Now, onto your questions...
I think that breast milk is the best for reflux babies cos it's easier to digest so please don't rush to change to formula without trying the elimination diet. The doctor is talking rubbish about you not having anything to eat. I went through the Total Elimination Diet where I ate nothing but rice, potatoes, squash, lamb, turkey and pears for 2 weeks and then slowly re-introduced different food groups to see if dd reacted to any particular one. More details on this diet here - www.askdrsears.com/topics/feeding-infants-toddlers/food-allergies/elimination-diet. I'm not saying you need to do this, just that it's possible and not that hard.
If you decide to trial formula, there is no point using the usual type as they are all cow milk based so if your dd is cow milk protein intolerant, she'll be even worse on formula. You need a prescription for anti-allergenic formula like Neocate or Nutramigen. These are quite expensive so GPs are reluctant to prescribe them but you can insist on a 2 week trial. If you can't get this formula on prescription, you can get it yourself in a pharmacy, they are not prescription items but are quite expensive, the Neocate is around £30 for a 400gm can, you may want to pay yourself to trial it and then if it works, the GP is unlikely to refuse to prescribe it to you.
Please don't feel pressured to give up breastfeeding if you don't want to. I am going through DD refusing to feed (bf) due to reflux but I'm still breastfeeding her when she sleeps as she eats then or give her expressed breast milk by a spoon as she won't take a bottle, it's really hard, often very upsetting and time-consuming but it's worth it for me as I think she benefits from my milk and I don't think that she'll be better or it'll be easier on formula although I have to admit that I go through stages where I feel I can't cope anymore! but then you do somehow....
All food labels will say if a product has dairy (including proteins like whey or casein or buttermilk, cheese, cream etc) or soya in them, you do have to read the Ingredients section, it's a bit tedious at first but you quickly get the hang of it. Have a look at this website about breastfeeding and eliminating foods from your diet - www.kellymom.com/babyconcerns/food-sensitivity.html
Your baby doesn't need to be loosing weight to be referred to a pediatrician, insist that GP gives you a referral because your dd is in so much pain/discomfort. Let us know how you get on!