A pleasure, sir. I'm relatively new here but I went to town when I started so I've gotten to know the scene moderately well. I really dig it!
I liked Vipassana originally, having practiced it scantily for some time but I found it lacking when I hit what you guys would call 3rd Nana, as my mind seemed to get really messy, and this messed with me so I quit.
Are you trying to get enlightened? Why are you pursuing Buddhism? I'm interested in seeing why you're still going at it.
The thing with vipassana is that it really begs for completion. In looking into the 3 characteristics, it seems that we get closer and closer to directly seeing how we end up perpetuating dukkha. Once we see it clearly enough, there will always be a sense of living in dissonance with that, until enlightenment happens. This is why vipassana doesn't function well as a salve for pain or angst, and can actually increase discomfort. Your body, mind, emotions, paradigms, basically everything will be in hell at some point in vipassana, although there are pleasant points as well. But the point is that we're trying to see exactly why the pain, angst, discomfort can come about. When you get to the end of the nanas and get a fruition, you permanently destroy the mechanism.
This comes directly from the teaching of seeing the suffering, seeing the cause of the suffering, seeing the ending of suffering, and seeing a way to go about ending that suffering.
As far as the angst goes, I'm sympathetic to your story. I grew up with similar feelings. I felt like I was different, I felt like I thought in a way other people didn't, I felt like I was some sort of mis-manufactured person, contemplating but not being able to contemplate to any kind of satisfying end, wishing I could just give up the tendency to contemplate and just think about sports and pizza and silly youtube videos and girls. The feelings of angst and tension escalated to the max and I was basically at the bottom of the barrel, feeling massively alone, depressed, helpless, and up to my neck in pain that I didn't even understand the cause of.
Of course, these feelings don't necessarily have to have a spiritual, meditative cause, and it's always possible they have nothing to do with dharma and more to do with situations in life. But why are you so interested in Buddhism and meditation? What are you trying to do or figure out? Why do you spend time on forums like this? Haven't you seen how consistently people report negative feelings of angst, misery, and existential troubles in dark night territory?
If I'm understanding your existential angst correctly, you've most likely opened Pandora's box, and the only way out is forward. I'm not trying to sound intimidating or dramatic, but people who gain insight to reality to some extent are honestly likely to deal with the implications of those insights until they can find a way to shut them out, or until they get enlightened and permanently resolve the issues that those insights caused.
If you consider yourself stable and rational, I would encourage you to keep going with vipassana, with resolutions for stream entry. If you're interested in Buddhist teachings and alleviating suffering, the fruit of the path lies in doing vipassana. If you're truly not interested in walking that road, I'd recommend practicing jhana, or some form of concentration, as concentration tends to be soothing and stable. I wager that the existential problem will continue to arise though, and if that is indeed the case, I am certain you'd find the relief from that in getting stream entry. I certainly did.