Why won t Facebook show me any new friend requests?

Ok so I have about 4,000 friends on Facebook. For the past month or so people will request to be my friend, but I won t get any notification about it. Even when I check my friend requests, nothing shows.. I did an experiment with my someone who added me on Facebook, no notification or anything again, but when I searched up his name and went to his page, it gave me the option to confirm or deny his request. Which I did and he was successfully added to my friends list, so me having exceeding my limit of friends isn t an explanation. but without me searching up the name I would have never known he sent the request.. This is becoming real annoying because I m missing a lot of friend requests and I find myself usually stumbling across pages who have sent me requests that I didn t even know about.. Is anyone else having this problem or can tell me how to fix it? Thanks