I am sorry for what you have gone through. I answer question after question on AVVO telling people over and over that they probably do not have a "bad faith" claim. HOWEVER, it sounds to me like you have done everything right to secure a claim against your own insurer! In particular, you served a CCP 998 Offer to Compromise (not a 1099!) and you beat it---Bravo! This could establish a prima facie case against the insurer for unnecessary delay and "low balling." Since it is a First Party case, you can allege a claim for Breach of the Covenant of Good Faith and Fair Dealing.
Please take a look at a couple of my links below regarding UM Arbitrations and CCP 998 Offers to Compromise.
Best of luck in your "next stage!"
There seems to be a basis for a bad faith action although more facts will be needed to assess your damages relative to this action. Contact an insurance attorney to review your possible case. You can find one through the Avvo search.
Sounds like you had an attorney who represented you - that is the person most knowledgeable about the facts of your case. You should direct your question to that attorney
This is not intended to be legal advise or as legal representation. I am a California personal injury attorney . Be aware that every state has its own statute of limitations; and statutes & case laws that govern the handling of these matters.