I can't see crap in the second vid so I'm going off the 180. I watched that about 20 times to try to analyze what's going on.
It looks like you're starting to counter rotate your upper body prior to the pop. You can do this on a 3 but shouldn't need to for a 180. You're also looking straight down instead of just watching your landing. Are you looking at your board? You'll see that your upper body opens up but then just kind of hangs there at 90. After that you're hucking your lower body to force the rest of the rotation. Also why you were off balance when you landed.
Honestly I'd say your 180 needs to be practiced and cleaned up before you attempt your FS 3. That needs to be clean and smooth without the 90 degree upper body freeze. I'd say that's why you're not completing a 3 rotation.