@Morkonan: Funny you should mention return rates, in all honesty, I've never had one product returned from a customer, not even so much as a complaint.  Only a couple of technical situation in which a customer didn't understand.  On my renders here, yes, I can see that the IDL lights aren't doing justice on her specular values, the IBL lights show them though, so I'll have to play with the lights some.

Can anyone tell me if she looks adult or not?  I've not had one respond on that since I changed her body morphs.

If you haven't had any quality concerns or legitimate complain returns, then pat yourself on the back for knowing that the customers who purchased your products were satisfied with their purchase. That is meaningful, no matter how disappointed you may have been with this particular product's sales. But, remember - A potential customer only knows what you tell them. If you're wondering about why someone may not have bought what you believe is a great product, THAT is the first thing you must examine, always. Did they know it was a great product? Be sure to answer this in your marketing, else no magic pixie dust is going to be sprinkled around which informs them how great it is. (You can not count on word of mouth, alone. "Word of Mouth" doesn't pay your electric bill. :) )

As far as an "adult" looking figure, I'd say she was in her 20's or so, given her... somewhat statuesque build. (Wide hips, plenty of jiggly bits...) There's a small amount of neotany going on there, but not enough to make the character look entirely juvenile. Neotany characters are fairly popular, but without exception, they're all adults, even though most "fairy" producer's characters wouldn't be given driver licenses in most states in the US, if only their faces were used as a criterion.

Note: The bottom lip needs a bit more bulge and more cleft beneath it. Check the original V4 head mesh and note the edges where these adjustments need to be made in your face sculpt. Pay close attention to increasing the bulge of the lower lip and the cleft that needs to be there and where, exactly, the original edges for those features are on your sculpt. Those areas get lots of deformations in certain default expression sets, so you want your custom sculpt to deform well with them.

The eyes may be a smidge too far apart. That's not, necessarily, "wrong." But, you might want to bump the eye-size a small bit (.2, perhaps?), if you plan on keeping the eyes spaced that far apart. (Check morphs like squint and some brow-lowering morphs as well as the eye/cheek morph (whatever it's called) to see how the eyes look with these morphs at or around 1. Then you'll know what you might want to do to improve their look, if needed. Yes, you're a slave to V4's topology, even though it's your morph. :) )

Because of the sever nature of the custom lips, somewhat subdued since you started reworking them, you may wish to consider making a custom smile and frown morph as well as pucker and pucker wide. (Or, just one custom pucker that can be substituted in lieu of V4's various pucker morphs, which will likely be called by many Expression Packs your customers might try to use.) V4's smile and pucker morphs tend to use up a few more faces below the lips than one would think. It may be due to there not being enough of them, there, considering all the other expression deformations. This tends to cause quite a few faces around the mouth to "move up" the face of V4 when smile morphs are used, often resulting in what can only be called a "poop-eating grin" effect found in many custom face morphs when "smile" morphs are used. :) The cleft below the bottom lip can also get over-pronounced in custom face morphs when certain expressions are used. (You'll have to check a few of them to see if that happens in your case.) Again, an issue due more geometry being needed there. (That's not a dig against V4! She's got plenty of geometry to play with. It's just that getting custom faces and their topology, that are very different from the original's, to work well with all of V4's expressions can be difficult to do, at times.)