Welcome aboard - you can ask us anything here - there are so many of us that there is always someone that will be able to relate entirely! I'm a grandma helping to raise my grandchildren too! Seems to be more and more of us!!! I thought getting older was supposed to bring peace - ha! Love them dearly tho, couldn't picture my life without them, ADHD meds and all!!!
Linda
Hi BamBam! Hang in there. There is
information in books and online that show that untreated Adhd can lead
to depression, self medicating with drugs, etc. Most parents try
structure and other methods before resorting to meds. The behavior
therapist sounds terrific, especially since you think he/she has some
good ideas. 
I am the daughter of an ADHD OCD parent, am ADHD, the mother of a daugher with ADHD and the grandmother of two girls with ADHD. The eldest (16 yo) was the youngest child diagnosed at NIH at age 3 and the other is ADHD OCD and is exhibiting Turett's Syndrome symptoms.
I raised a daughter w/o meds (she's 40 now) and she suffered tremendously. No one who does not have this can truly understand what it is like.
You are doing the right thing for your grandchild and he is very lucky that you did something about it. Just ask your husband if your grandchild had diabetes would he object to insulin?
I posted a message a few days ago and have since had my grandson to the doctor.We took him off of Concerta and put him on AdderalXR. Will see if this helps any. He's a great kid and I would be lost with out him but he does use up alot of my energy some days.