Try to add the dick adding a real dick png transparent template.
Here are all you can need.
imagefap.com/pictures/8609907/dick-PNG
Maybe you're using a model what deforms the penis, but with a real base the results are better, and you gain precious seconds of hair-dick interaction because the dick is already in the shot. If you don't want to use photoshop in your computer, you can use photopea, even on a phone.
I don't know what model you use, but for now, unlucid is the best one.