Caffeine and successful FET?!

I had planned to go caffeine free post FET (three days ago) but was so low energy and constant headaches. I caved and had a coffee today with maybe 60-80mg caffeine which is obviously under the 100 recommendation. But now I'm spiralling and thinking I've ruined everything. I usually only have about 80mg (one coffee sachet) per day for the last maybe 3 months. Please tell me your success stories?

I'm annoyed with myself for caving but also so so much more alert and active most coffee, which is surely a good thing?

It's my first FET.