Should I move on to IVF?

Hi everyone, I tried to conceiv with my ex husband for a couple years and was unable to. Now, I have been trying to conceive with my boyfriend for a year and a half, and still nothing. I was told that I'm ok, but my boyfriend had a normal sperm count, low motility and 0% normal morphology. We have already done 3 IUIs with clomid and all were negative. They are letting me try one more iui with femara instead of clomid because I begged them. They told me that they would not let me do any more IUIs and that I need to move on to ivf after this, but I'm nervous. My insurance covers IUIs, so can't I make the decision to do more? The dr is saying no. I don't know what to do. I'm just praying for a successful iui #4 so I don't have to worry about this anymore.