((((Big Hugs))))
No, you're not alone! I also have a 7 year old son. We've tried sports too, but either his attention span isn't long enough, or he's not interested. Right now we're in cub scouts. They seem to be more accepting of his quirks. I hope it lasts.
I get sad when I hear other Moms talking about their kids sports. DS show a little interest, but practices are usually after school when his rebound is at it's worse. He also does 4-H which allows him to choose the activities he wants to do. It's great because it gives him time to be around other kids and away from the computer and video games. He also learns a lot. It's not year round though, usually just briefly in the summer until they're older.
Does he have a friend that he can connect with? Or even a cousin? Someone to share sleepover and playdates with?
Have you tried bowling or swimming?
No you are far from alone.
Until we medicated our son, we had similar behavior.
Our son is adhhhhd and couldn't control it himself. He is also impulsive.
Meds saved his life. He is 12, a A student and successful.
I am sorry for what you are going through. Have you thought of medicating him? We started when our son was shy of 7. We just couldn't let him suffer anymore.
I read the bottom of your signature. If I a may ask, how is your 17 year old son Andrew? You mention anxiety and depression. Are they being treated? Is he ok?
I hope you don't mind me asking, I just care and want to help. 
I know exactly how your feel, but what helps me is that I know that there are no perfect families. There is always a little something going on under other folk's roofs. They just keep it secret and put on an image.
I know we are busy with our's but I treasure mine, really really do. They have so many great qualities. I would trade them for the world.
May I ask, are you treating the bipolar first and then went back and treated the adhdd? How are things?
my son is adhhhhhd and sensory and speech delayed.
My oldest was diagnosed ADD when she was in the 7th grade. The bipolar was just newly diagnosed, but the ups and downs have been with her for a long time. I'm more than a little confused, and honestly can't tell you where the ADD ends and the bipolar starts. I'm inclined to think the behavior has been there for a long time. It's is just that now she is too big and independent to pick up and put in "time out". Often there is simply no reasoning with her. Is it bipolar, normal teenage rebellion, or ADD? Who really knows? The constant turmoil is wearing on the whole family.
She has been taking Vyvanse, Lexapro, and just recently started Abilify. Her doctor has warned us that there may be several modifications to her meds before we get it right. She is her own worst enemy. I try to be supportive, but must admit I have some very mixed emotions regarding her.
LAHdedah40142.3497106481My son is 12 and starting to come into himself. He is a good kid, cares about his grades, but boy the mouth is fresh. He is really into the video games, not a socializer outside school but has friends in school. He loves the xbox.
I wish you strenght, patience and success. I also wonder if it is the teen stuff. I remember being moody. They have so much stress on them now.
How is her social life with friends at school?
jaxx, I have been where you are! I'm still there sometimes!
I look at other kids and I try not to be jealous but it's very hard. My son is almost 5 and it's just been a recent thing that he can walk next to me on the sidewalk. Before now he'd be running out into the street or just plain running off! I see people with their 1 year olds that are able to walk quietly and it amazes me! I love my son sooooo much and wouldn't trade him for the world but I wish he could have it "easy" the way I see other kids. He has to deal with so much in his little brain. 
Once we got my son's medication right the whole world changed! Things are MUCH better and I don't feel as jealous as I used to. He still has many more problems than your average kid but nothing like before. Keep at the medication...if things don't work, change doctors and keep trying until they DO work. There is something out there for him, you just have to find it. 