The Only Thing to Fear is Autism Itself

Have you ever been worried... like REALLY worried that something was wrong with your child?
There's so many disorders out there. There are so many things just lurking around to make life harder for your little one.
For the longest time, I've been worried that Tyler has autism. He is a sorter, an organizer, he can spend all day lining his cars up, and gets really upset when they are disturbed. He doesn't really like to be held or cuddled, and sees being talked to as an interruption. He took a long time to learn to speak and until recently, was not a big "look you in the face" type person. He knows his numbers, his alphabet, his colors and shapes... even obscure ones like trapezoid and aquamarine. His first words were the letters of the alphabet.
Feelings, actions and consequences (especially emotional ones) were beyond him, as were any abstract thought processes. He knew and loved solid, factual things (This is the number 6, or this is the color orange) and felt uncomfortable with things that weren't so solid. (Giving Mommy a flower made her happy, or does having that boo-boo make you sad?)
For the longest time, I was terrified. To tell you the truth, I've been putting off his Dr.'s appointment because the developmental testing is coming up.
And then he started speaking.
Like I said, he was a late speaker. He started saying his alphabet at 18 months to 2 years, but I almost don't count that; he didn't say much else for the longest time. Right before his 3rd birthday, he started speaking conversationally. He can express and idea, a want, or tell you what he's doing. He's even expressing and understanding feelings, in himself and others. He doesn't do sentences yet, but at the rate he's progressing, I'm no longer worried. He seems to come up with something new to say on a daily basis.
He still doesn't want to be held and loved on (unless he's sick) but it's just a boy thing, I'm told.
He cradles my face in his little hands when I'm crying (usually from taking a toy to the nose)
I attribute a lot of this to his sister. She's a gregarious, social little beast with no sense of personal boundries, and no like for toys of any kind, only the human face and human interactions. She refuses to let him sit, lost in his own little world. He loves her and hates her guts in the same breath.
I'm scared she's going to be talking better than him in a year. What do you say to people when your 2 year old is talking their ear off, and your 4 year old is still speaking in fragmented sentences?
I even took the Autism Spectrum Test, and just applied the questions to him, rather than me. (The online version is by no means a professional determination of autism) To be honest, his score was within the range, but just barely.
I'm not killing myself over this, partially because of his great social strides, partially because of what my mom says, "All kids develop at their own rate." and partially because, you know, he is who and what he is, and it's not going to make any difference in me loving him with all my heart. A diagnosis of any kind would never change any part of that.
But my heart still climbs mountains when I see him playing with other kids, or telling me not to be sad, to be happy, and trying to turn my frown into a smile (I admit, I fake cry to get this from him) When he kisses his sister or lets her help him with his cars, even though she's messing them up a little.
They say, time will tell. And time will always tell the love I have for Tyler.