Faint Positive/Negative Blood Test

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AF was supposed to come 8 days ago. I’ve taken an hpt and got a faint positive then all negatives after. I’ve been experiencing cramping for the last 7 days but still no AF or spotting. Went to the ER and had a negative blood test as well. I am NEVER late on my cycle. My husband and I began TTC last month. Anyone with similar stories?