Yes it is certainly very difficult to wait on test results.  You can just about make yourself nuts wondering about the what ifs....

so my daughter.....  I adopted her from my youngest sister at birth.  She is now 21.  When she was 2-3mos old, I noticed her crossing her eyes.  I thought it was normal part of the muscles teaching themselves how to focus.  Her ped said no and sent us on to an opthamologist.  Who checked her out and sent us to a real expert optha.  Anyway at 4mos she went on in to the second doc.  He found that she has optic atrophy in both eyes--her right worse than her left, hypoplasia, crossed eyes, nystagmus. Frankly the nystagmus is much more noticeable later on because eventually her eyes self-corrected the crossed eyes.  Weird- huh?  Optic atrophy bascially means undersized nerves.  The hypoplasia means the nerves are pale .  Her pupils are almost always very dialated unless we are in very bright sun.  This leaves her "legally blind".  Which is odd because no one would ever look at her and think so.  She has depth perception probs, when she wants to see something clearly, she brings it  to maybe 2 inches in front of her nose.  I think she can stop her eyes from shaking when looking closely.   Basically she uses what little vision she has very well.

Well if you have optic atrophy, could also have other issues with the eye.  Hence the ERG.  Basically it shows if the retina reaches back to the eye center of the brain.  It measures if the brain receives input.  In my daughter's case, yes.  Then off for the CT scan.  It showed a unilateral schizencephaly.  It's a very rare condition of clefts in the brain.  Basically she has gaps in her brain.  Where brain should be, she has just fluid.  The abnormality is often on both sides, hers is just on the right.  There are many variations of the clefts.  With each person, you have a range of mildly--to severely impaired.  Often children start seizures in infancy.  My daughter was odd here---she is severly impaired--autistic, spastic muscles on the left and a bit on the right, legally blind, non verbal---but she didn't get seizures until 13 and didn't start endocrine problems until somewhat recently.  We're not even sure how involved her endocrine system is.  Looking for an endocrinologist right now.   About 2yrs ago we finally had an MRI to get a REALLY good pic of her brain.  21yrs ago the CTscan was deemed sufficient for dx.  Honestly the MRI just gave a more detailed view of the schizencephaly.

 I just looked back on my kids' baby books.  #2, #5 were sitting well at 7 1/2months.  #3 --8 1/2months, #4 8 1/2month  and #6 well must've been too busy to write it down.  But I think she was in that range.  My #4 has a bit of lower muscle tone, so she was behind on all the gross motor.  She also has some kind of language processing issue too.      My fourth child qualified for special preschool because of language and PT/OT for her lower muscle tone.  #6 had speech articulation probs which we nipped in the bud with speech when she was 3.  She scored high verbally we just couldn't understand her!! haha The rest of the little buggers are doing very well.  #6 just started kindergarten.

Remember children develop on their own timetables.  Plus the ranges for milestones are fairly wide---like walking 10-18mos is in the "normal" ranges.  Somewhere around there. My number 6 was 14mos before she walked BUT her fine motor skills were waaaaaay ahead.  #2 was probably 2 3/4yr old before he could talk in sentences, BUT he qualified for gifted/talented in elementary school.  #5 was singing twinkle twinkle well and understandbly at 19mos, yet she's my biggest clutz.  Probably because she looks anywhere but forward when walking/running.   

I'm thrilled that your son's scans came back normal.  Definitely a PHEW!!!  Now nail biting for the bloodwork.  Hopefully all will be fine.

Good luck