I listened to a lot of your samples, and I'm not going to dissect your audio performance (although I do commend you for being willing to let people rip your playing apart). But one thing that you mentioned that immediately put up a red flag for me is, you said you hum the hi hat rhythm (sort of like beat boxing it) while you play. That suggests to me that you may be focusing more on the microbeat than the macrobeat. And that may be what's making it hard for you and the drums to lock in together consistently. It's much easier to deviate from the tempo (and play tug of war with the drums) when you're feeling fast 8th or 16th notes as a bass player, instead of focusing on the slower 1/4 notes (i.e. the macrobeat), which is the groove of the song. I suggest that you really concentrate on that macrobeat 1/4 note, and let the microbeats just fall into place on their own.
I know with my drummer, if the pocket starts getting loose, I'll look directly at him and start bobbing my head and whole body to the slower macrobeat (the groove of the song that the crowd dances to), and the pocket usually locks right in immediately. And as a bonus.. it just looks like were rocking out to the crowd, while we're really correcting timing/rhythm errors on the fly.