Reciting softly in fajr when one is performing Salaah individually

I was praying my Fardh Fajr Salaah and I did not recite loud like I do in the loud prayers and more like how I recite in the quiet prayers and so I continued reciting how I was so as to keep consistency in the salaah. At the sitting position in the second rak'ah, I said up to "Ashhadu anna Muhammadan 'Abduhu Wa Rasooluh." and said "Assalaamu 'alaykum wa Rahmatullaah" to my right then faced forward and prostrated (I intended to do the two prostrations of forgetfulness for not reciting out loud like I usually do for Fajr Fardh). During this, I got up from prostrating and raised my index finger and was about to start reciting "Attahiyyatu lillaahi Was-Salaatu Wat-Tayyibaatu." But then, I was confused whether I prostrated once or twice, and I leaned to the decision that I had only prostrated once so far and so I said "Rabbighfirlee" three times and prostrated for what I assume to be my second prostration. I sat back up and said the Tashahhud, Durood and Du'a, then I said both Tasleem. Now I wonder is my salaah valid?