Insurance offered me $8,200 for my totaled car - KBB says it's worth $11,500. What do I do?

So my car got totaled last week in an accident (other driver's fault, they ran a red light). I've been paying full coverage on my own vehicle too just in case, and now I'm glad I did - but their adjuster just called with an offer of $8,200.

I looked up my car on KBB and it shows private party value between $10,800 and $12,200 depending on condition. Mine was in really good shape - new tires last year, no prior accidents, regular oil changes. I've also been searching local listings and finding similar cars selling for $11,000-$12,500.

Is there a process for negotiating this? do they have to accept my counter or can they just say no? And is it worth getting an attorney involved at this point or is that overkill for like $3,000?