I'm one of those annoying (to you) people who doesn't have any trouble with blood sample taking, in fact, my veins are so good I have sometimes had blood taken without a cuff! I am surprised that blood is being taken from the back of a hand as mine has always been taken from the inside of my elbow. I suppose because I've got such good veins they don't even bother trying anywhere else.
If your sugar levels are quite high when on the tablets then it's really worth trying insulin, it's not half as bad as you probably think. The needles are so much shorter than you think as well. Depending on how much fat/flesh, call it what you will, the needle may not need to be very long. I haven't got much fat on me so I am using the shortest one - 4mm while my friend who has quite a lot is using a 12mm needle. Injecting doesn't usually hurt, in fact the finger pricking is worse. I have been on insulin for about five years and don't always get good sugar levels but it depends on so many things like exercise, stress, what you've eaten etc. so it's sometimes hard to get it right. I am quite sensitive to insulin so I only have about 5 units per meal although I have a demi pen, one that gives half units and it's surprising what difference half a unit makes. I would much rather be on insulin, even if I do have to inject four times a day, three with meals and one before bed, at least you can adjust the dose whereas if you're stuck with tablets you can't do anything about it at all. You have to be careful of hypos and, of course if you drive you have to tell the DVLA and will be given a three year driving licence but as long as you are careful and make sure you don't go too low it's no problem.
If you are getting stomach problems with Metformin, are you taking them with food or just after food? Sometimes I have forgotten to take my tablet for an hour or so after I've eaten and when I do take it I get a bit of stomach ache. When I was first put on three a day I had to keep rushing to the loo so I stopped the lunchtime one but I started it up again a year or so later and it doesn't seem to affect me now. You should really think about going onto insulin and perhaps your sugar levels will be much more stable and there may be less need to have blood samples taken so often.