It's good to ask even if she has to say no, and I'm sure she will want to help you. The thing is- without the risk of asking, there's no potential for more help at all- because even if she had to say no to bi-weekly or to holding onto that knife, she might be able to offer something else that would help.

Your impulse right now to ask for biweekly sessions and help to counteract the self-harm impulse is SO healthy!!!!!

Listen to and nurture that voice, you deserve it.

I am sorry you are suffering, I understand your fear of making things worse *especially* with your past experiences, but I really hope you will trust your healthy instinct to ask for help when you need it.