How can you determine how much is your case worth?

I never knew it would be so difficult, after you have been in a personal injury case. Your lawyer never keeps you, updated seems my attorney plays the silent treatment daily with no phone calls , No calling me back, No follow thru when you do finally get someone to talk too. I was speaking with a Pain Management firm and the Doctors secretary told me she is in a car accident and , I ask her how do you determine how much is your case, and she told me its based on the other at-faults insurance on how much is their policy worth, is this a true answer and if this is a true answer , then lets say if they only have a insurance of valued at $30,000 is this the most you can collect, due to all your suffering and pain, or is there another phrase to the settlement. I see on attorney's web-sites just for a spinal injury just due to L-5 disc, they get their clients over $450.000 and I have disc L-3 thru L-5-S1 and also T11-12 protruding from my my accident, Due to a MRI-results, my doctor says on his reports: Severe LBP with Bulging disks, with arthritis, with forminal narrowing. Can any lawyer tell me is this case only worth the value of the 3rd parties’ insurance coverage? I am on the verge of finding me another attorney if any attorney can give me some advise and I am in Texas also. Seems the attorney I have was recommended to me by the MRI-firm to get me a LOP , is the only way I could get this MRI-done which my chiro-needed done without the wait any longer.