Sometimes for me, when I'm scared about other, current things, I revert to thinking about things in the past. They're "safe" to think about because they are already over and can't hurt me anymore. Too, sometimes when we look back over our childhood we think we were "supposed" to feel bad about something because other people would have so we unconsciously feel bad that maybe we didn't feel badly about it at the time? I had a heck of a time in therapy for 25+ years thinking I should feel a certain way about my mother's death when I was 3 but I just don't. I was sheltered and taken care of well, etc. and don't remember her or anything "traumatic" and that boggles my mind that I am not upset in a particular way. That doesn't mean it didn't affect me, but the effect was "different" and it is my job to look for that effect (such as you worrying now about why you're thinking about it now, so much later when it wasn't "much" at the time) that is unique to "me" and work with that. Something obviously affected you that day, you just don't know what/how. I still needed a mother and when I got my stepmother I "merged" the two mothers together only my stepmother was not my mother! For a really long time in therapy I did not have a "name" for my real mother, and could not refer to my stepmother as my stepmother! You may have done something with your memory/the experience of that day and woven it into you life in some way that ultimately does not help you but which is a "new" trauma/problem you need to work through like I had to separate my mothers. It wasn't my mother's death that affected me but her "absence" when I needed a mother and my reaction to my stepmother and her presence and how she didn't "fit" right but I "made" her fit.

Don't spend time feel badly about yourself Rio! There's nothing wrong with you, your psyche is doing its job and helping you. You are always on your side and what you do/think/feel/experience is always "yours" and "good". Treat it like a good mystery or the thread from the yarn going into the dark cave :-) and work with that when you get a chance. You don't have to solve it all right now (I was in therapy basically from 1970-2005) and there's nothing bad/wrong with you for any way you feel or don't feel!

Maybe start with trying to see when these "thoughts" of the previous experience/memory come to you; what are you "doing"/thinking right before in the "real"/now world? That will be a clue as to why you're trying to "dwell" back there. Work and uni and all those things are new, scary experiences for everybody! You made it safely past the old experience of being a child and the counseling, etc. Maybe it will be interesting to see how you feel a month, then six months, a year, etc. into uni; right before you graduate? :-) and when dwelling on the old thoughts come up. It could be that "simple", the childhood experience could be a "talisman" of sorts.