Advice needed

Went in for my mid cycle ultrasound - I have two follicles that are almost mature, I believe she said around 17, but lining is only 5.7! I'm on day 12. I am going back in for another ultrasound tomorrow to see if things progress or not. I am hoping to do my second <a href="">IUI</a>. Last month I was on the same meds and I had thick lining, large follicles, good timing for <a href="">IUI</a> but still got a BFN
Dr had said to try 3 IUIs before moving to <a href="">IVF</a> but I'm starting to wonder if 2 is going to be my limit... I have PCOS and this is our 14th month TTC. I am so depressed these days. Any advice or encouragement here? I know maybe I get ahead of myself with being so down about my ultrasound today.. but it's hard to see this going well after all that has consistently gone wrong.