Brother I used to get this, the fact you hate it is a clear indication of iman, the shaytan does not annoy the kaffirs to commit shirk at they already do it, Some sahabi asked the messenger of Allah sws about this they said there are things in our hearts we would rather burn to a cinder than mention, Mohammad sws said is this really true, they said yes, he sws said, this is clear iman.
The type of waswaas you are speaking of is a sickness like any other, see sheikh munajids website islam qa type in waswaas not only are you not accountable but you are rewarded inshAllah according to inb taymia! ignore it akhi and seek refuge in Allah swt. Don't play with it in your head! Say the dua ''I seek refuge in Allah swt from shirk and that which I am unaware and that I forget" Relax akhi if you really were a kaffir would you hate it?? A kaffir is happy with his kuffr the fact you hate it shows you are pious inshAllah ignore this stupid shaytan his plot is weak I had this for years, the more you try and think and answer it the worse it gets, seek refuge in Allah swt ignore it, and praise Allah every time, if every time he sais it you praise Allah he will stop because it will be a source of your reward, email me brother if you need I have a lot of experience with this, but chill inshAllah you are not a kaffir if you were you would not be bothered by it!!! We know there is no God but Allah swt and we believe in his messenger sws and everything he said Allah swt does not make a muslim a kaffir so easily if your niyah (intention) is good Allah swt will protect you from kufr and the grip of Allah swt is a trustworthy grip, do not be paranoid brother just keep confirming your faith in a prescribed manor also knowledge kills the shaytan it is your best tool against him read kitab al tawheed by ibn Abdul Wahab or watch it explained by salam al amry on youtube, I know him he is a very straight man clean aqida, that will clear up the problem, like I said tell me privatly what the problem is dont tell people on here so the shaytan cannot make it a fitna on them, Salaam