3rd Cycle of Clomid with no ovulation.

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I have PCOS, I can't ovulate by myself and my periods are crazy because of this. I've been taking Metformin as prescribed by my fertility specialist, as well as Clomid. I'm about to begin my third round but I'm losing hope. I really want to stay positive but it's hard.
My first cycle was 50mg, and my Day 21 progesterone level was 2.4. No ovulation.
My second cycle was another 50mg and my progesterone was 1.3. Even lower!
My specialist can only see me for 6 cycles worth of Clomid (I'm in the UK and 6 cycles is all you're allowed for free on the NHS). She said she will increase the dose to 100mg for the remaining 3 cycles but I'm hoping when I see her this month that she'll allow me to have 4 cycles of 100mg, since I've proven that my body doesn't respond to 50mg. 
Has anyone here been in a similar situation to me? Have you had a few cycles of not ovulating and losing hope, but then started to ovulate? I'd love some success stories, and/or any tips!
Hubby and I have been tying to conceive for 4 years now. 4 very long years.
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