Very Late Period - Is That a Thing Mid-Winter??

So today my period is 18 days late... I’ve take four pregnancy tests all 100% negative. My period is usually pretty much right on 31 days apart give or take a day or two, except for last January when it was also late (not this late though)... Is this because I’m not getting any sun or something (I live in the Pacific Northwest). Wondering if this later period in Jan/Feb happens to others...

It’s also the first time my husband and I have tried to conceive sooo it’s a bit frustrating to be up in the air about this. Currently abstaining from alcohol just Incase I am actually pregnant and all FOUR tests were wrong (possible but not likely, I know 🤷‍♀️)

Anyway, thoughts?!