To Learn the Alphabet - Week One: Letter "A"

So recently I noticed that my son hasn't mastered the alphabet yet.  Not sure if he 'should' have by now, he is almost four, but either way it is all my fault that he hasn't.  I feel like I have failed him.  He is very well spoken, uses great vocabulary but again has not mastered it.  I have been teaching him the letters, unofficially like any other parent I know since forever.  Singing, pointing out, occasionally doing fun alphabet crafts, and surrounding him with educational toys etc.  I read to him every day, but yet the other day I asked him with flash cards what the letters were, he kept guessing and joking around.  His primary language is English now, but he is familiar with two others spoken around him.  I just am in complete shock, and feel horrible about it.  Again, I know every child is different and learn on their own speed, that he will learn eventually, but I know he knew them so it is time for me to remind him...

Also I honestly feel like a year ago he knew the alphabet better than he does now, perhaps I stopped pointing it out as much because he had it down pact..but now he has forgotten?!?  This has driven me to start a little "school session" at home for at least two hours focusing on a letter a week.  I'm not a mom gone crazy, it will all be fun.  I don't like my baby to miss out.  We do "table time" everyday were we do some kind of paper craft, but now I will do that with more of a "lesson plan."

Today was day one, letter "A."  We had fun reading, practiced writing, coloring, singing, gluing and of course going over what the letter A spells.  Snack time included apple sticks.
..ignore the huge scissors I was using. lol :)

He made an "A" poking around w the toothpick he was eating with...

Not all children learn on their own and figure it all out right, right away right??      :)