Very strange, my uptime went a bit up in the last days. So I encountered the exact contrary phenomenon.
Your uptime SHOULD go up "a bit" over a period of a few days, right? And asymptotically approach 99.99%.
My question is, how do you know if you've missed a forge you were supposed to do in a cycle of 101 blocks?
Yes. You can check in the forging center if you forged the block or missed it. The interval of your forged blocks should always be between 0 and 101 (1 and 100).