I know how you feel about asking for help, the fears, the thought of just voicing it is so daunting.
If you are unable to do any of the suggestions above try doing what I do when Im scared of myself and cant voice how Im feeling to those close to me.
Write it out in a note or email or even send a copy of your msg here to your dad. He sounds like he really cares but doesnt know how to reach you or help you without you rejecting it. This way you dont have to see his reaction when he reads but can reach out to him indirectly. He will help you if you try it. Im a parent, I know he will do all he can if you give him a chance.
I hope you find an answer soon, its a tough journey we are all on but you are not alone.