i can't really answer your questions thoroughly, i can only guess.
from what you are writing, i think that
a) you have a very mild case of this condition, you can be glad that only your upper lip is affected
b) the white area around your affected area most likely has nothing to do with healing, this condition almost never heals from outside inward and if it does, it only takes a very short time because the underlying cause (eg. systemic disease) is cured. (in this case, it completely heals within 1-2 weeks). EC usually does not heal gradually, either it resolves completely very quickly or it just gets a little better and stays that way. as you already noticed, it's the same for you: your condition got slightly better but did not entirely heal. it is very likely that, for the moment, they will stay that way.
as i already said, all i can say is that you can really be happy that it's only your upper lip that is affected. NOBODY will notice it. pretty much nobody notices that i have it and about 1/3 of my upper and 2/3 of my lower lip is affected. most people taking a closer look think that they are dry, that's all.