Honey! Dont worry! I know SO MANY people who have a hard time with IVs, i was one of them. I also have veins that are all but impossible to see, so i hear ya!
I can intubate, cath, and lance with ease, but those DARN IVS! I get stressed just thinking about them! It does take a lot of practice, and it does get easier. I am not sure how MUCH practice it takes to be really at ease with it, (I am NOT to that level yet, still shakey).
I know this might sound bad, but a lot of the people you will be doing IVs on in the hospital are "old" people, with protruding veins, and not much of a fat layer to try to see through. Some of the veins "roll", but it is easier to hit them if you can see them.
Be proud of yourself though! Atleast you hit the vein at all. My poor lab partner got stuck 3 times by me before I ended up getting the vein at all. Advance is a "touch", and is learned by feeling the walls give, and how the ONC travels (ONC=Over-the-needle-catheter). Just breathe
It will be ok, and you will get better. Practice makes perfect, right?
Smile, it makes you feel better