Morph target? If you have enough edge loops, and spend enough time tweaking (soft selection in 3dsmax, if you're using it), it shouldn't be too difficult.
*Walks in as the stench of forbidden man-love clears* The upper lip profile seems a bit straight instead of curving and looking soft. Nice work though.
Ok, i found a way to "solve" the problem roughly, even though the result is not 100% accurate, using front view/ soft selection scaling, but it's really close to what i wanted, just the edge are a little bit squeezed.
Okay I'm probably going to study the XRK M4 from MW2019 a bit since this is pretty much spot on to what I am now trying to achieve (https://bcog.artstation.com/projects/YaAEgw). I also just bought a texturing tutorial by Dan Kenton so that should also help with the process. About this, those are not shading issues but…