Basically the nominee to a bank account, after the death of the account holder, the nominee can withdraw the amount as a nominee, but it becomes his duty to disburse the amount to all the legal heirs of the deceased account holder.
A nominee's job is simply to receive the funds from the bank so the bank is freed from liability. The money belongs to all legal heirs according to the laws of succession (e.g., the Hindu Succession Act or Indian Succession Act, depending on religion). As both you and your brother are equal legal heirs, all of your mother's bank balance must ultimately be divided equally between you two, regardless of who was named as a nominee on which account. Because the principal amount itself is subject to equal division among legal heirs, the interest earned on that principal also belongs to the estate (the total pool to be divided).
You do not have an exclusive right to the interest generated by that money just because you were the nominee or withdrew it. The court will likely calculate the total value of your mother's estate (all accounts combined) and adjust the final settlement so both brothers receive an exactly equal share, including any interest accrued. If you paid income tax on the amount you withdrew, that tax deduction must be accounted for before the final division.
Since your brother's nominee accounts have more money, the court will likely subtract what you already withdrew (and the interest you owe him) from his larger share, balance out the taxes you paid, and order the bank to release the remaining difference to you.