Have you still been doing the weight training too? I know how you feel, although I can clearly see that mine is down to muscle growth (don't know how I feel about that yet, I suppose it's better than fat
) but also my arms have literally only changed about 0.5 of an inch since starting losing weight.
Could you maybe up your leg work, squats, lunges, etc to keep toning? That's all I can think of, other than that we may just be cursed with thunder thighs