Peculiar Experience of Shamatha / Vipassana

I'm currently attempting to do shamatha and vipassana meditations in alternation, even though I'm unsure this is the best way to proceed. I noticed that generally, as a person, I am somewhat repressed in the sense that few thoughts, images or sensations seem to emerge. There are a few other peculiarities I experience, and I'm unsure if people could help me with that. I remember vaguely as a child having odd sensations / visions which arose without reason, in mandala form usually. And since a while now, I seem to be gaining insight randomly, sporadically. I've been happy for years, not in a strong pleasant sensation but in experiencing equanimity generally or lack of attachments. Yet, I'm feeling stuck in my practice because I don't seem to realize where I'm at. I don't know whether I have good or bad concentration, or whatever else. I seem to be unaware of my own mental states. Since I feel repressed and few images or feelings arise, I think perhaps vipassana would help, but ultimately, I dunno. Any kind of help on what I'm experiencing would aid me greatly, and I'd be willing to supply more details if necessary.