Very possible. Very very very. let me show ya
Note the fertile stuff early on (the big blocks of dark purple, if it's dark and a full box on top, that means ewcm), had the classic temp dip.. and nothing...
you have to figure out what your daiy to day goo is like too. That was the hard part for me. I always "feel" wet. I may not have any cm, but I feel ooey and goey. I'm also more likely to have lotiony CM than I am sticky. So my BIP (basic infertile phase) is creamy/wet and my fertile phase is eggy white/lubricative.