I have always had a line in between my nostrils- what is this? (Rhinoplasty?)

We have very limited view of your nose and based on that rhinoplasty or fillers will fix this. The case of this is separation of the lower lateral cartilages. Please see the link

Hello timetotransform,There are naturally two pieces of cartilage that start in the middle of your nose, help form the tip of your nose, and spread out over the sides of the nose.  What you are seeing is the edges of those two cartilage structures because you have very thin skin.  You can undergo a procedure to help camouflage them with rhinoplasty (although you would not remove them or your nose would collapse) although that won't necessarily completely get rid of them.  The other option is to use fillers to make it less prominent, although that is temporary.  The last option is now realizing that they are a normal part of anatomy but simply visible on you because your skin is thin and you do nothing about it.  If you are contemplating doing anything, I'd recommend you consult with a facial plastic surgeon.  I hope this helps and good luck.