First beer jitters are always an issue. I still remember mine. Here is my 2 cents though. You saw signs of fermentation, so just let it ride. Honestly, since something started, at this point there is nothing you can do to change the course, other than monitoring and controlling your temperature. So best to just let it ride for 10 days, then check your gravity.
The idea that airlock activity is not a good indication of fermentation is a true statement, especially since you did see activity. So, weather it's bubbling fast, slow, or ends up stopping, that doesn't mean fermentation is done. Again, once you see something, give the yeast the time they need to do their thing.
The only time I wouldn't follow the airlock mantra, is if I never saw any bubbles in my airlock. The only reason I say that, is because I have never had an airlock not bubble. So, in that case, I would be worried that it didn't take off if I didn't see anything within a couple of days. At that point I would take a look, just in case it never started and I needed to pitch new yeast.
Your fears are understandable at this point, we all have to learn somehow. Just for future reference though, once it starts, just let it do it's thing, there isn't a whole lot you can do to change the course it's on, once it's started. Opening, checking, taking samples, imo, these are all ways you can ruin a beer. Compare that to just letting it do it's thing, there is no way you can ruin a beer if you keep the lid closed and let it ferment.
Don't worry though, most of us started out just like you, once you get a few under your belt, you'll begin to say, "Oh, it's doing this this time.
