What did I write that sounds ISFJish to you? (Sorry, I know you said you couldn't pinpoint it, but couldn't help asking :happy

I'm just trying to get an idea.
OK, I'll do my best. I'll have to make some generalizations, to which there are always exceptions.
-I feel like I generally take things at face value, and then remember to analyze them.
An INFJ is more likely to analyze things first, and often keep analyzing them, and less likely to see things at face value. INFJs usually don't need to remind themselves to analyze things - they just do. It's like second nature.
-I easily get jealous of and am possessive of my friends, but don't show it.
It is my personal belief that INFJs are just as susceptible to feeling jealousy, possessiveness and envy (and any other intense emotion) as an ISFJ or any other type. But I believe they would be less likely to hide it. I know that I can't hide negative feelings and neither can most of the INFJs I know. In my case, although it may not be typical), I don't feel jealousy or possessiveness of anyone.
-I cannot or do not bother to predict the outcome to books or movies. Twist endings almost always take me by surprise.
INFJs and most intuitives would be able to predict the outcome more often than sensors. Some are really good at this and they have fun trying.
-I am insecure- when someone compliments me on working quickly, I always get paranoid that I left something out. I often feel like I'm not good at anything.
Anyone can feel insecure, and INFJs especially so, but you said that you would be paranoid that you
left something out. I could be wrong but I think that an INFJ would be less worried about having left something out and more worried about what someone will think of it. They may be more worried that they offended someone or effected someone in some way, or even possible that they may be judged.
-I envy people who don't seem to let anything bother them. I often feel weak because I'm overly sensitive
Me too! Except I don't feel that being highly sensitive makes me "weak", just sensitive. It depends on how you define strength I guess. Does bottling up ones emotions (or just not having any) make them strong?
-I love the idea of being part of a group- when everyone depends on and cares about one another. I like assembly lines.
I think INFJs are more likely to want to work alone or in small groups. The assembly line thing sounds ISFJ to me. I think it would make many INFJs shudder.
-Intuition confuses me, period. Maybe I'm thinking of it in the wrong sense.
Not usually confusing to intuitives. We know what it is - we live by it.
-I often imagine elaborate conversations with people- real, fictional, strangers, and friends
So do I. I'm not sure this is indicative of any particular type.
-I enjoy analyzing friends and fictional characters
That could definitely be INFJ, and maybe less likely to be a sensor trait, but what do I know?
-I don't mind breaking rules and sometimes enjoy it (when doing so doesn't hurt others in any way)
There is a thread on this right now in the INFJ forum.
-My dad frequently gets frustrated with me because whenever he asks me a question, I think of why he's asking that question and answer that instead of the actual question.
This sounds like an intuitive trait to me.
-From the type descriptions, a world of "hidden meanings and possibilities" seems much more appealing than one that is "concrete and kind"
"Concrete and kind" isn't exactly an appealing alternative to "a world of hidden meanings and possibilities". What if they had worded it differently, such as "Beautiful, solid, stable, and kind." Would that make a difference?
-I have trouble understanding basic logical concepts.
That just indicates you are not a thinker, but doesn't say much about whether you are a sensor or intuitive.
-I have difficulty "living in the moment"- I'm always worried about what's going to happen next
I sometimes have this problem too but not as much as my ISFJ friends. Some of them have a really hard time letting go of the past.
I hope this helps, I had to think about it for a while.