Hello BWXD, i hope my asia-english is not cause any confuse, and i hope that i can help.

I just have finished my Texture Analyses Exercise a few day ago, so i can not point any mistake that you made. But i can give you some advice through my experience about Texture Analyses Exercise (yay :>) .

First, you can use another pen that have smaller head to detail the texture intead of your pen.(which you used in your old exercise). It will make your texture more detail than last.

Second, when you look at any texture, try to brainstorm which part will be drawn dark and which part will drawn light, then try to draw it on the paper (thinking about where the light come from, and why the light doesn't come there would help). To do this, it could take you for and half of hour per texture (but it worth). If you can't see any dark part and light part, just try to analysis the partern of texture and copy them on your paper.

Lasthing, thank you for reading, stay safe now and have a nice day