Welcome! Glad you found us! Always glad to see people starting to compost - best thing you can do for your garden as well as keeping all that stuff out of the landfill.
I would keep adding to it for awhile. As you have seen already compostables reduce in volume dramatically from the original materials to the finished product. Your pile isn't just compressing, it is breaking down. If you were to just make your original pile and never add anything and leave it to finish, you would come out with a tiny amount of compost, like I don't know, at a guess a couple cups full. And it would be less likely to finish up well, because the composting process works best in a bigger pile to hold the heat and moisture in.
But at some point you do need to quit and let it finish. What I do is keep two piles. One I am building and adding to all the time. After that one has been building and working for several months (in growing season or all through the winter), I take all the (uncomposted, still recognizable) stuff off the top of that pile, down to the layer where the earthworms are, and use it to be the bottom of a new pile. The stuff at the bottom will be finished or nearly finished compost and will finish up quickly, exposed to air and stirred around a little. So then the second pile is finishing and being used up. After it is all used up, that site can become the location again for the building pile, so I just have two spots that alternate back and forth which one is building and which one is finishing/ being used.
That works for me. Some people have three piles. That partly depends on what volume of compostables you have.