Sorry, but I'm not going to be nearly as kind as others have been. I would have kept silent till I read that you planned to take the most precious cargo in the world for rides with it: your kids!
What I see in those photos is a recipe for disaster, add in pain and death if it ever saw a human passenger. Pics aren't clear enough to tell for sure but that looks like hardware store all-thread as your main support structures? Do you have any idea of the actual metallurgy and strength of that stuff you used, that's possibly made in China depending where purchased? That is its strength in relationship to Grade 3, Grade 5, Grade 8 or ungraded?
With the all-thread bolts hanging out in space what's supposed to support sidecar dynamic loads, cornering forces, flexion? The metal tab used on that front support clamp doesn't look nearly thick enough to function as a clamp, even enough to withstand necessary forces to tighten it in place, let alone support a load.
The tubing dimensions look too small and too thin walled for any genuine structural integrity or load-bearing strength. There's a direct relationship between tube dimensions/wall thickness and structural load carrying ability. I'd say you need to do more research there. Also gussets are needed at all angled joints, especially the rear.
As that's currently built I would hesitate to use it to hang a heavy saddle bag. I'd have kept my mouth shut if it wasn't for the possibility of that setup causing extremes of pain, injury and even death for whatever innocents get involved. Please do more research and accept the other member's prior suggestions and offers of guidance. I just don't want to see you or anybody else get hurt or killed, especially your children!