If it is the front lower nose blister you are working on I think you are going to want to shoot for something like this...



Here is the reference image I grabbed off google images...



I made it really fast so I did not think hard about optimization and it's not a perfect match but it's close and demonstrates the process. From the reference the blister is really not a perfect hemisphere. So I should have cut it a few faces up from the equator of the original sphere.

It is basically a 20x20 sphere (default). Deleted the lower half. Created a 1x1 poly plane and then positioned it to cut out the planar part. Did a boolean difference. Cleaned the mesh. Extruded the frame parts. Extracted the flat glass piece. Grouped it all up, deleted the history, etc.

Here is the .ma file if you want to take a closer look at it...