Hi WebbyR,
It’s not really possible to tell much from an outline or even a single picture because each person is very different and has their own alignment range where they don’t experience any symptoms (see post #7 here about “learned” alignment vs a “theoretical” best alignment for example) and the actual symptoms you experience are always more important than “theory” but the alignment in the outline you drew looks fairly good compared to the illustrations here and there is only a slight spinal curve which is fairly normal when you are sleeping on your side.
Having said that … If a blanket under your pelvis area reduced or eliminated your back pain then it certainly seems that your alignment is benefiting from center zoning in your mattress. Again … I would always go by the symptoms you experience more than any “theory”.
“Comfort” is strictly subjective so I’m not sure what it means to you or what would make your mattress more “comfortable” for you but I would always prioritize alignment and the elimination of any specific symptoms that you are experiencing over more subjective perceptions of “comfort” anyway (comfort is often just a matter of getting used to the feel of a different mattress) because you can’t feel your mattress when you are sleeping so your body will respond to alignment and pressure relief over the course of the night much more than “comfort” or how your mattress “feels”. Your mattress is fairly firm apparently (based on the description because I don’t have any personal experience with it) so if your alignment is good with center zoning then depending on what you mean by comfort it may be worthwhile adding a relatively thin topper to the zoned mattress to improve your “comfort” so that you can work towards having the best of all worlds (good alignment, good pressure relief, and good “comfort”).
Phoenix