Tbh mate youre probably not balding. Im no expert but lots of peoples hair clumps together when wet and shows bits of the scalp. Its normal.
Go watch the movie warrior with tom hardy, when hes all sweaty u can see his scalp and hes not balding its just natural. Weird example i know but its where i first properly noticed it, quality film too.
The fact its similar to the sides of youre hair show that youre hair all over ur head is the same.
Dont stress about it too much, keep pictures of your hair and monitor the difference, if things change that youre balding, untill then enjoy ur life stress free from hair loss.
All the best