Hey, you're doing just fine! As many mares as I've foaled out, I had one that I decided wasn't pregnant every other day! And she was an older mare, and her belly changed constantly. One day, I just decided she wasn't pregnant, and I put her back in pasture with the other mares and their foals, and unfortunately checked later (since I didn't have another mare due, so took my time) and found my "heart" filly -- dead. And she was everything I'd waited for in all my years of breeding this one particular stallion!
So, they can be very confusing. I could have kicked myself! But, you're doing all the right things, even if it turns out she's not pregnant, although it really seems she could be! So, keep up with what you're doing, and it will be the best for both of you!