Blood work

I got my bfp last night on a first response digital. I called my doctor this morning and she sent me for blood work. My veins are alwful and always have been. I drank a lot of water to make it easier but they were only able to get less than half a vile and they need to do the beta test and progesterone. Has this happened to anyone else? Were they able to get what they needed with a small sample?