How do you know if you are having a sensory overload?

Hi everyone, sorry if I'm posting so many questions, I don't know who else to ask as I am still waiting for my assessment!

I do have some anxiety and irritability/anger issues and I'm trying to figure out whether they might be triggered by something else than what I initially thought, and I started looking into sensory overloads and overstimulation. Every post I've seen or video I've watched, the person could explain in detail what was causing the overload. Do you all know? Have you always known, even before you knew you had ASD? Or is it something that you learned to analyse and notice, and as a result now you know what is stressing you out?

I do have a sensitivity to loud sounds and mess/clutter, whether it's visual or audible. But I've never considered that there might be a link between these stimuli and my stress levels and reactions to other events. I once heard an analogy explaining why some autistic kids have a great day at school but have a trantrum when they get home. That they are like a bottle of Coke that's being shaken all day, and when they finally take the cap off in the evening the bottle explodes. So my question is, was there a time when you were having these experiences, got overstimulated but didn't react until later because you were subconsciously trying to cope and take it in, and therefore never made the link with what was causing the anxiety or irritability? Or are sensory overloads always obvious to you and therefore I don't get them?

Were all these aspects of autism always clear to you but you just didn't know that they were linked to autism? Or did you slowly notice and understand more and more about yourself and your behaviours and reactions?

Thanks!