Extreme waswasah and ocd

Assalamualaikum, When I do taubah or do anything through dua my mind makes oaths and then I forget whether I say it verbally or not . But my mind says that you say it varbally 100% but I know that when I was doing taubah how can I make oath. Is this a kind of waswasa . Do I need to pay kaffarah ? I am so depressed that I want to suicide or leave islam . I know that certainty is not affected by doubt . But I don't know whether I am certain or not . Please help me and write in detailed in this regard. I am very depressed.... I am not able to concentrate on studies 😭😭. I sing a music and then I suddenly stops and make a taubah but my mind says I am swearing not to do it again but I not said It verbally and immediately stops and then open my mouth and wait 2sec and complete the taubah . My mind says that you made an oath in 2 sec but I did not hear any sound but my mind says you are 100% surely taken an oath and after taubah I do the same thing again .do I obliged to pay kaffarah I am in doubt or maybe not in doubt .please help me .