I keep thinking that you are a T, the "F" qualities you talked about in most of your posts are not really relevant (though you did not say anything that could indicate T either when I think about it) because they are mostly "human" reactions (no matter how unemotional thinkers like to pretend they are) in my opinion and I know that as an INTP (or I think I am one, I was wondering whether I could be a feeler or not before), I can be very uncomfortable and immature with my feelings and emotions and used to based my personal ideal (not about humanity) on having a good heart and being sensitive because it is a positive trait for many people.
Inferior Fe, I think, makes me feel a need to be part of the community and understand people and convention while not being good enough at it to really get intentions and social conventions (though my brother who is an ISTP is good at it, it depends on how developped our functions are) so I can be suddenly paranoid when I feel that something isn't quite accepted but don't manage to justify the feeling logically.
Also, empathy and sympathy are something we can feel, it's just not a major part of our life (I still have trouble accepting that fact sometimes because it tends to make us "less" of human beings), however we don't always act accordingly.
Trust is something that can be linked to Fe but everyone has their personal history and reasoning when it comes to that. I don't think it's a feeler or thinker trait but I could be wrong.
I am extremely loyal to people I consider to be real friends, I don't think it's a thinker trait either.
As for complaining about life, I've realised that everyone does that to some extent, it depends on our current situation and whether we are positive or negative but it has little to do with feeling or thinking because everyone had thought about an ideal or dreams and has to face things that are unwelcomes, whether we express it or not does not really tell a lot about our type.
Wanting to understand people isn't really significant either in my opinion, the way you do your research might be more interesting however since feelers seem to see it as more natural and linked to emotions, empathy and something I don't quite get while thinker are more likely to analyse things and make logical conclusions about behaviours, etc.
Or that's just my friends and I.
The thing is, thinkers do feel. Some will avoid conflict more than feelers depending on how they function, INTPs also dislike criticism (especially younger ones apparently) but on the Internet, we tend to be more of a stereotype whenever we discuss types.
Sometimes it seems that you just have to say that you have feelings, are a theist and have a few friends with a messy room to be an INFP. In real life, it's much more complicated than that, sometimes it is really hard to really determine the type of someone and only introspection can really help you a bit on this question since you need to know what you are using but in the end, we all think and feel, we just approach life differently.