Centers do indeed have different guidelines. For example, our local center will not take living donors who smoke - period. Even if they quit smoking. Yet others do allow donors the ability to quit smoking and subsequently donate. Same with weight. I was also a prospective donor who had to lose weight. After the initial bloodwork, my A1C was .1 over the normal range, and I was told that to go further in the testing I would need to lose weight and the A1C and glucose test (they made me do two to be sure) were normal. In my case, the excess weight was indeed my problem and, once it was gone, my numbers were well within normal range.
I don't know your individual situation or if there are other concerns involved, but you may want to check with another center as an option. The real key, as has been stated many times, is that, for your own sake, you need to be absolutely sure that you can keep your weight and health in check over time so that you do not become the next transplant paitent.
Best of luck, and congratulations on the weight loss.