Depends on how the account is set up. She may have all rights to access the account and that could mean you cannot access the account without her when you turn 18. We here on YA really have no way of know just how this is set up for you.
You most likely can't access it. If he set the account up to be in your mom's name till you were 18 then she is the one who controls the money in it. That is most likely the case unless your dad set it up with another relative or friend or the bank. I do believe you can find out that information. Generally with these types of accounts your name is on it, but you just can't do any cash transaction unless it is a deposit, but you can find out info. I think.
you have no access to the funds at the bank until you are 18. whomever is custodian on the account in your behalf will access the account.
It depends on how the account is set up, but your mother probably has control of it until your 18th birthday.
Undoubtedly the money is either in her name outright or in a trust fund with her as the trustee. She controls it.