I used patches for a long time, but I've also tried gel. My endo told me that people's absorption efficiency from patches varies a lot, and I don't think they worked very well for me. Gel was often very noticeable, but probably because I usually applied far to much, and together with patches.
Regarding water retention, I don't suppose you started using spiro when you changed?
From everything I've read I doubt where you apply patches or gel makes any difference. I read somewhere that the recommendations for location in the packet are due to testing and approvals - they tested in a particular place so that's what got approved. I don't know if either of these is actually true though.
Perhaps your breast growth when changing is just coincidence? Mine used to come and go, and was quite unpredictable. Its not stopped hurting at all since starting implants, which probably goes to show how ineffective patches were for me.