TTC for way to long!!

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I feel like its been forever!! Tried 2 years before seeing fertility doctor. I have been going to this fertility doctor for a year now taking letrozole 5. Had all the blood tests done. Had hsg test done. He says every is fine. My husband was checked he’s fine. So what the hell?!?! I take my vitamins and do everything right. Why is so easy for some and so hard for others?