I have believed in Purgatory from as far back in childhood as I can remember, just as I have believed abortion was murder from as soon as it occurred to me someone could do that heinous deed, and this was in the absence of any significant early Catholic education. I am certainly no Saint and did the usual wild teenager things but have never wavered from my fundamental Catholic beliefs. Maybe the Holy Spirit provided some assistance along the way?
I often wonder something similar. It appears that God leads His elect differently: some grasp the faith as children and it remains with them since childhood. Others go through much struggle as adults:
 I am the good shepherd; and I know mine, and mine know me.  As the Father knoweth me, and I know the Father: and I lay down my life for my sheep.  And other sheep I have, that are not of this fold: them also I must bring, and they shall hear my voice, and there shall be one fold and one shepherd. (John 10)
During my conversion to Catholicism (I was baptized Orthodox) I often marveled: -- "Why, this is what I always believed". But I never had ANY religious instruction as a child. It just felt as if I knew what I was not really told.
And your Guardian Angel.