Tessa, I hear you and understand what you are going through. My Riley is/was difficult too when it comes to getting and keeping his attention. I posted a few threads in the "Showing and Training" section concerning this.
I have to say what has been working lately for me is what has been said by others, "relax and try not to be too tense or try to get things too perfect". I did the opposite for months and it was just a disaster for me and Riley. Now that I have tried relaxing and enjoying our walks, he actually pulls a lot less and is not so intense. It's going to take a while, but I can see improvement now where there wasn't any before, regardless of the treats I was using. Some dogs are just different and require a different way of training than others. Hang in there and try the relaxed method. It really helped me. There is a light at the end of the tunnel.