If you are happy with the brow placement then don't stress about the bottoms not aligning. Once it is riveted you can carefully try and even the bottom out but (as stated above) the bottom parts of the ears will cover that. Plus the s trim on the bottom can cover a little of that as well.
Here is the bottom of my unfinished AP. I will end up trimming a little more off the bottom to get closer to the bottom of the ear, s trim will easily cover the rest.