Sister Isha Khan, Alhamdulillaah you have zeal to stand for a long time in salah. Although you adopted a wrong way, but you did it due to a good intention. So InshaAllaah you'll be forgiven, don't be upset. Btw, why do you not perform "Salatut Tasbih"? It's a long nafl salah highly recommended by Rasulullaah .