I think either option is ok at this point, and you'll need to decide your own comfort level. I'd want a reliable weight from an accurate scale though first before making a decision. If she has a full 2lbs, she's unlikely to gain that overnight. If she only has 1lb, I'd likely turn her ff'ing now.
If you have bad roads in the winter, and she's 33lbs, I'd be inclined to eek out that extra 1lb to keep her rf'ing through as much of the winter as possible. If she's at 34lbs now, then I don't think there's much choice... The seat won't magically fail at 35lbs - especially if it's installed more upright. But I'm not a fan of repeated & regular weighing, I'd rather just turn ff'ing and not quibble over 1lb if she's already 34lbs.
She is pretty close to maxing the limit on her seat and she will be safe ff'ing now, it's just winter that would make me want to eek out a little longer if possible.