To go along with MissBrahmsRN, after you release the tourniquet, wait a little bit, because if you've hit a valve, it might relax, and then you can get through. As for 18s in everybody, I think that is crazy. I work onan iv team, and I was taught smallest gage to get the job done.
I graduated 3 years ago, and have been trying to get an L&D job (or anything maternal/child health) since then, and have had no luck at all. I started in tele, and now do that pool. I also picked up another per diem job doing iv therapy, and absolutley love it. I'm still trying though to get into L&D. Good luck with whatever you do.