Amy_R, just keep at it.
I go to the gym as well and not always perfect with my food hence the up and down losses, if I eat properly it tends to be 3 to 5lbs off a week, otherwise 1.5lb to gain, never had more than 5lb in a week.
There have been several weeks that I've felt so fed up and whats the point, hence the slow eight weeks. But believe me it feels AMAZING when it happens and you look back, completely motivated again, got a new gym buddy, and for the time being life is good.
One thing I've realised after nearly ten years over 20 stones is that you will get there if you want to, but you have to really want it. So many times I'd lose maybe 2 stones then give up again and put it on back on plus some. It feels different this time because I'm thinking differently, not a diet, but lifestyle change. Still struggle often but I don't beat myself up when i slip now, I just work harder the next day with syns or gym work.