blood test help!

Hi everyone. I have been trying to go for some 1st trimester blood screening at my doctor's office. The hospital requires certain tests to be done so they can be prepared when you come in for delivery. They want to know blood type, etc. There are also some optional tests, which I opted in for- cystic fibrosis, NIPT (reveals trisomy 13/18, down syndrome, some other genetic disorders, and gender). Later in the pregnancy I will also have a blood test for spina bifida and a check for glucose. I am worried because I have been to the office twice now for testing and they are having a hard time getting the blood they need. In two visits, I have been stuck a total of 17 times with a needle and all they have managed to get is the tests required by the hospital. I have enough bruises on my hands and arms now to look like an addict. Does anyone have advice on how to make this easier for myself? I have always had some trouble with nurses finding a vein, but never like this...