My port was moody too. I had mine repositioned because the Muppet who installed it made a critical error but the second try left a slight kink in the tube which showed up when they did a die test. I found that if I positioned myself with a pillow in the centre of my back and my shoulder pulled down it worked. Massive contortions but what ever it takes... It was slow to draw bloods but functioned well enough for infusions. When I had it removed we found that I'd grown very attached to it and there was sheathing on the tube which can form a bit of a plug at the end. When I say I was attached to it, you can read that as I'd completely surrounded it with scar tissue which probably explains why it used to be so sore. Painful or not, it was much better than the alternative.
The stabby nurse thing is difficult, isn't it? I let them have one go then politely ask for someone else. Don't feel bad about doing that, this is not about them and some people may be assessed as competent but have no talent for finding veins. If you know one of them is no good, have a quiet word when you arrive and say you don't want to be assigned to her. You do have a choice--you wouldn't let a hairdresser who had already given you a crappy cut have another go would you?
The nurses in our chemo unit are excellent and go to great trouble to get it right. If I have to have bloods taken--i finished chemo in March 2017-- I give them a call and pop in at a time that suits them. I won't go to either of the pathology services because there is no way of knowing who you will get and they are in too much of a hurry.