u/dad-dont-do-it

Hello everyone, I've been using the lovehoney high roller for sometime and only today have I felt a decent amount of stimulation when i lay on my side and try to pry the toy so that the head hits the prostate but it aches my arm after enough time. I dont know if im doing the right thing I feel pressure in there etc. but cant quite get anywhere im not sure if the high roller is even hitting my prostate if i dont try to move it forward with hand intervention. Should I use a different toy if so what? Thank you so much and sorry for the long paragraph.

edit: is my anatomy or the toy the problem or maybe both?