When is it time to get a second opinion?

My husband and I have been seeing a fertility specialist for about 6 months. We've done 3 rounds of Clomid w/ timed intercourse and trigger,  3 <a href="https://glowing.com/glow-fertility-program">iui</a>'s w/clomid and trigger and 1 <a href="https://glowing.com/glow-fertility-program">iui</a> w/clomid, Gonal-f injectables and trigger. With not results. 
We are told we have nothing wrong with us to cause concern and we are actually pretty fertile. I also have a 6 year old from my previous relationship. 
I'm just wondering if my doctor has missed something. 
I need some opinions please. We took this past month off to give my body a break.