Either color would work fine with the pink blouse and shoes. I would personally get lavender because it’s one of my favorite colors, but either would work well in that coord. Maybe decide based on the rest of your wardrobe and which color would fit in better.
My first thought is that you have to find a super cool way to incorporate leather. I’m not sure what color leather your character would wear, but my character wears black leather armor (although hers is studded) so that’s what I automatically thought of and I thought of two options for it. My first thought was to do something like this awesome synthetic leather skirt in black and then wear that with a black blouse. You could also do a pretty femininely cut leather jacket but I’m not sure if I would do that with that particular skirt because that might be too much. Maybe a leather jacket over a black JSK though. If you were to do the leather skirt, I would personally wear it with a blouse in a nice flowy fabric and maybe add a pretty corset. Either that, or a somewhat simple blouse and a black capelet.
Another thing I might add, which I don’t think I would add to a Lolita coord normally but I would in this case because of the theme and the fact that you have short hair so it would be easily visible, would be elf ear cuffs. There are a lot of them around etsy (I personally really like these ones) and I think they make really interesting pieces of jewelry, especially in situations like this, without looking super costumey.
Coord is short for coordinate and it’s the exact same as an outfit, just a different word for the same thing. Coordinate is often used in Asian countries and is found a lot in Japanese and Korean fashion magazines which is why it’s used so often.