OCD - wanting to understand thoughts

I think I have a sort of strange version of OCD where rather than not wanting to think thoughts, I feel I have to think about them to understand them properly. I think it's the same basic problem of not understanding where the thoughts are coming from, but in my case I'll quite often be thinking about any kind of topic and suddenly have a feeling that I've 'missed something', in the sense that I've assumed or understood something implicitly, but can't describe to myself what it was. In a very simple case, I could be out shopping and totting up the cost of what I've bought, and get it wrong, and then not only do I feel the need to correct it, but I need to understand where I went wrong, in case there was some kind of logical gap. I.e., the need to 'misunderstand' the numbers again to figure out why I didn't understand them initially. Weirdly I don't have any issue with the idea that I might have done a '2+2=5' in my head, but I nonetheless get an overwhelmingly strong feeling that I need to know, and I'm not even sure what it is that I'm afraid of - some kind of logical void maybe? My thoughts are normally more abstract and sort of pseudo-philosophical, but it's almost always the case that I feel like there's some concept that has flashed through my mind very briefly, but and hard as I try, I can't bring it back. Similarly, but related to emotions rather than concepts, I sometimes feel like I have memories of being a kid, or I see a certain place, and it gives me a particular feeling or ambience (most of the time quite nice, to be honest), but again I get this inexplicable feeling of not being able to explain it, like remembering seeing a snowy scene as a kid and feeling it looked 'magical', but not quite being able to recreate in my mind exactly why it felt that way, or why looking at it as an adult would feel different. I understand that memories are imperfect, and I'll never be able to recreate exactly how I felt, but in the same way as the concepts, I feel like something fleeting has happened in my mind, and, extremely frustratingly, I can't explain it or bring it back. 
For me it's more a constant low-level irritation, but every now and again I'll get a spike of anxiety about something, especially where I'm trying to recall a thought while talking to someone or doing something brain-intensive, and I'm trying to both concentrate but simultaneously hold onto the thought.  Sometimes it can be gone in seconds and I'm left with a feeling of unease about a general topic, but with this gap in my memory about exactly what I had an issue with. It's almost like a conceptual version of being able to experience a new colour and then losing it, and not being able to ever convince yourself that you could recreate it in your mind again.
Trying to psycho-analyse myself, I've always been very 'purpose-driven', and often worries about things seeming meaningless. I now think that as well as trying to find (or create) meaning in life, I've now developed an intense fear of my own thoughts being meaningless.
Weird as this sounds, has anyone else experienced anything similar?