Troubles with synthroid?

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Had a miscarriage in June and we’ve been trying since. They did my TSH and said it was high so they put me on synthroid. I’ve been on it for 6 weeks now I’m 5 days late for my period but getting all BFN... is the synthroid throwing off my cycle? The doc said it could be stress but I’m always 28 days and I wouldn’t say my stress level has changed at all from last month to this month...