If you're still confused, I suggest learning function theory for the MBTI. I really did think I was an ISFP for two years before I realized the functional makeup was very different. INTP uses Ti-Ne; while INFP uses Fi-Ne. The difference there is that the Ti type makes subjective thinking decisions--logic is their preferred mode of decision-making (highly internalized problem solving skills)--and uses Fe to make Feeling-based collective decisions, more concerned with the status quo. The Fi type will do the opposite: make subjective Feeling decisions when it comes to then (internalized morals and values establish their core).
For what it's worth, I have a Libra sun/rising, Pisces moon friend who is an INFP too, so you're probably right!
Many thanks Bluebell! I like to think of myself as dangerously loyal