Nurses or Blood Donor Techs?

[janette]

I have a question about blood donation. I try to give blood when they come to the office every quarter. The last 2 times I've tried to donate my blood has clotted. The first time after the bag was almost full and the last time before it even started. I also have rolling veins so it makes it hard sometimes for them to find a vein. They are due to come in a couple of weeks and I'd like to know if this is something that will continue to happen? My aversion to needles hasn't gotten any better from this, because I've had some nurses / techs require more than one stick to hit a vein I've always been a little nervous about it but try to do my part. Should I give it one more try??