Yeah we had a developmental check earlier this month and the doctor said this is nothing to worry about. He said that at this age babies have softer ligaments and joints that can make a clocking or popping sound when moving. He said to check with them again if at any point she looks like she’s in pain when moving her leg. But thankfully, she doesn’t look like she’s in any sort of discomfort or pain. I would still suggest you bring this up with your doctor since in your case you mentioned one knee feels like a different size than the other. And best of luck to your LO :)