Hi Allen,
Looks fine to me. The profile you're working from has the outer white roundel rings a little too wide, I would make them thinner outlines.
The story of their development may help you understand the strange appearance:
In the Indian Ocean/CBI the UK learnt to eliminate the red colour from roundels or fin flashes quite quickly. They replaced them by overpainting the red with white, or extending the blue to leave a small dot of white in the centre. This produced a lot of variations in appearance. Later still, sometimes they reduced the size of insignia to half the size carried in the ETO or MTO, thus producing aircraft with "small" roundels. All of the FAA aircraft were in 2 colour camouflage, so the roundels still stood out against the grey, green & sky blue.
Then c. January 1945, the US lend lease aircraft supplied started arriving in theatre painted in overall Gloss Sea Blue, & the blue roundels became difficult to make out against the aircraft colour, looking like tiny white spots from a distance. So the Eastern Fleet (Indian Ocean) started to introduce a thin white outline to the roundels, just to improve the definition against the Gloss Sea Blue paint of the aircraft. It's something unique to this theatre & timeframe (JAN '45 onwards).
The attached is depicting an F6F Hellcat, but it illustrates the proportions quite well, especially if you compare it with ETO roundel sizes & proportions.