I feel your pain on this one, my daughter was 8 weeks early, and I had trouble with my milk productions.
She was in the hospital for a month, and while she was there I pumped every three hours, and still didn't have enough milk come in. I was getting about 20-40 ml a pump, and that was with pumping for 20 minutes with an electric pump. So i tried drinking beer. No difference. I tried domperidone (I'm not sure if they prescribe it in England, but the Canadian Breast feeding association gives its stamp of approval) and although there were no side effects and very very little makes it into the actual breast milk, I only got up to 60 mls a pump. I was still trying to breastfeed Betty on my hospital visits, and having some success, but was still having to top off her feeds.
So I tried fenugreek, nothing changed.
To give you the flip side of this, I had to stop because I was killing myself trying to feed, pump and care for my baby while using as little formula as possible.
You will hear alot of people tell you that you just have to keep going and going, and that formula feeding is a lazy option (which its not, if you've ever had a screaming hungry baby in your arms and you are waiting for water to boil and cool to feed her), but if you're baby is not getting enough food, then you have to ask yourself why you are still so strongly breastfeeding.
I fought, and exhausted myself trying to breast feed, and I felt like I was failing my daughter. Finally my doctor said to me (and know that she is absolutely pro breastfeeding) that my daughter would be a strong and healthy baby (which she is) if I stopped trying to kill myself to breast feed. It wasn't my plan to formula feed, I'm still pretty choked up about it (I'm bloody crying as I type this) but if you need to, its okay to stop. You are still a great mother. Your child will love you just as much.
Just make sure you are doing it for the right reasons.
This isn't me telling you to stop trying, please don't think that. But its okay to give yourself permission to stop. You aren't a failure. You did your best, and you are still a wonderful mom to your child.
I hope my story helps, I really do understand how you are feeling. I was lucky to have many nurses and doctors and lactation consultants surrounding me during my trials, and they not only helped me try to bring up my production, they also helped me to let go when it just wasn't going to happen, because just coming down on yourself is not going to help.
I'm thinking of you, I know how hard this all is.