السلام عليكم ورحمة الله وبركاته احسن الله اليك I struggle with khushoo and focus a lot. (Alhamdulillah, it's getting better) I once prayed poorly without much focus or awareness, and at the 3rd/4th rakah, I also forgot which I was on, so out of embarrassment, I restarted my prayer. Is this wrong?

Ustadh AbdulAziz al-Haqqan

Yes this is wrong, follow what u think is .ostly the case, and if you do not know 50% 3 rakas 50% 4 rakas, then choose the less always so 3 rakas and continue, and make sujood assahw.