I am an INFP e6 artist and often test J, while my husband is an ISFJ e9 and exhibits many P traits - he is more spontaneous than I am in terms of actions and choices. However, he is a much more linear and organized thinker, while I am more whimsical and impulsive.
If you are indeed an ISFJ 4w3, it may be that your MBTI type is quite influenced by your enneatype. I would expect an ISFJ 4w3 to be particularly introspective, melancholy, emotionally turbulent, aesthetic, and sensitive as compared with other ISFJs. I was going to say check out Socionics but it looks like you already have. To me Socionics Si/Fe ISFp sounds more like the way you seem to experience them.
What exactly is it within Se and Fi that seem to resonate more with you than Si and Fe?