Hey AP,
Take a look at the shape of the nose. It's a perfectly round pointed cone. Your shading indicates beveled edge ending in horizontal blade-like tip.
Think pointed round cone. The shading lines should diminish to a single point point and the shading should be continuous from top to bottom.
Then you'll have a killer looking F4 nose cone
BTW, I don't envy you or any other F4 profile painter. That plane is FULL of complex contours! You'll really need to do your homework to get it right. Look at as many photos as you can and think those shapes through.