IUD curious

I'm 21 and have always wanted to get the IUD so one day I went to my gyn to get it placed but I was too small (doctor said I was too small because I never had kids but I'm rather small myself so..) 
Now I'm thinking that maybe I shouldn't get it because I like deep intercourse and wonder if I would feel it or if he would or if it'll move or hurt.
​Any thoughts..