Hi welshgirl,
I think the target is certainly possible. It would require a sustained effort (it's only just under 2lbs a week which I think is at the upper end of what SW says is 'average') however as you are near the beginning of your journey there's absolutely no reason why you shouldn't achieve it.
I'll do my sensible bit (as I say many times on here !) that if you are the kind of person who responds well to a challenge but if you're falling short that will be ok and you will keep going to get as close as possible, then absolutely go for it. If you're the kind of person who will give up if you're not likely to achieve it rather than looking at what you have managed even if it's not target, then consider setting yourself a slightly easier target and then up it if you hit it much earlier. I prefer to set smaller targets and then increase them if things go well but everyone is different here.
Good luck.
Gail x