So, I have a few questions to ask. But first thing's first, take a deep breath, relax, and focus. What makes you anxious about getting blood drawn? Has there been a situation involving getting your blood drawn that triggers your anxiety?
Also, have you spoken to a doctor about your anxiety? For being 14, it seems your anxiety is through the roof and you should be speaking to a therapist about it. This is something you need to explain to your father that this needs to be done. Brushing it off will not fix the problem.
You are right, he is not using the right approach. That is probably because he doesn't understand the fear so has assumed it can't exist in someone else.
Do you go to a large school where you can talk to a counselor about your fear, to see if they can help or if they can't, they might refer you to someone in therapy that can?