I think it's hard to tell how you're coming across, yes, but not impossible. If you get consistent feedback from others - either positive or negative - I think that can give you at least an indication.
I think you seem self-aware, by the way.

It's not completely cut off to extroverts.
I asked the initial question just because I seem to have had this sort of experience several times. On this site, a couple of ENTPs have - well, in one case definitely tried to flirt, in another case maybe? But when I took offense to something the latter one said because he was really pushy and I felt was trying to inflict some (to me, pointless) point on to me, he did this sort of eye-rolling "ohhhh...conversations with INFJs so often go like this" which was really condescending and just annoyed me more. The one who was definitely trying to flirt came on fairly strong and I was reserved and I guess slightly dismissive; then he was like "oh you INFJs, you claim you want guys who tell it like it is and then you make all kinds of silly assumptions when someone is direct with you."
I've also IRL had the sort of experience with ENTPs where you get into arguments and then they just dismiss what you say out of hand, it seems totally arrogant, and this with someone who I thought had at least some intellectual respect for me.
I have to admit, I don't really get the fabled ENTP-INFJ thing.

I can see how there could be chemistry, but beyond that... I dunno, maybe just my bad experiences but I wonder.