I was in a ped/auto accident in Texas. I'm the ped being hit by the auto. Am I not able to get more than the BI available ?

I do not practice in Texas, so I would consult with local counsel before relying on this answer. However, you pose a question of general law, so here's the general response:

Your recovery for bodily injuries is not, with certain limited immunity exceptions in some jurisdictions, legally limited to the amount that the tortfeasor (the driver, in your case) carries. You are entitled to recover the amount of your consequential damages, including disability, likely future health complications, pain and suffering, medical expenses and lost earning capacity.

However, your attorney is likely advising you concerning the more practical limitations; you can't get blood from a stone. Insisting upon seeking reimbursement for more than an insured's coverage limits will usually require you to try the case and obtain a judgment, which may mean a signifcant delay in your recovery. Furthermore, even if you were to obtain such a recovery, there are many ways to limit access to personal assets that will require significant litigation to get past, and there's always the protection of bankruptcy, which will potentially discharge a litigation debt.

You should sit down with your attorney and have him explain to you why in these circumstances he is strongly recommending settlement at coverage limits. He may have very good reasons beyond what your current understanding is for his recommendations. However, after hearing him out, If you're dissatisfied, remember that he works for you, not the other way around; you have a right to retain an attorney who'll follow your instructions, as long as they are ethical, and zealously pursue your claim to the limits you feel are fair.