I don't see a big dilemma here
INFP or INTP seems likely.The way you write reminds me of my own way of writing and I am INTP but that's hardly a strong argument. A notable difference between INTP and INFP is that INTPs keep their feelings to themselves and are better at gathering information and facts while INFPs are more communicative and expressive but usually prefer to ask a person that they trust instead of to try and work out the facts by themselves (or at least they often seek confirmation/consultation about the facts that they gather). INTPs might get annoyed at emotional outbursts from people around them and tend to focus on how to be optimal and delay doing stuff. INFPs have occasional emotional outbursts and are generally good in dealing with people.
Both INTP and INFP can be inert but INTP more so.

Edit: still ... by looking at your writing it seems precise (in terms of clarity) and structured and I associate that style with INTP.
Second edit: I might be blamed that I see what I want to see but what I think I see is that you are an INTP(ILI).