First off, i'd glance through this study

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743651/

Part of the reason I think that oxytocin doesn't work well as a pheromone is because of its agonistic effects on vasopressin bringing out more motherly behaviors and stress response.

I think that if we found a molecule lighter than oxytocin, that binded to the same receptor, but with an antagonistic effect on vasopressin, that it could be used tentatively as a pheromone.

Part of the struggle is that agonism of vasopressin by oxytocin, the stress response.
Should one be able to activate oxytocin and inhibit vasopressin, you could create an aura of trust and interest or even love. There are a number of possible chems, Inotocin, way-26474, and a host of other peptides. Now all I need is a sequencing lab.

Please don't mind my rambling, i'm writing this after being up way too long.