I agree, many l;adies do not even notice their mucous plug, and many dont loose it until they're fully dialated either, so just because you havent seen any sign of it, theres no need to worry, its a great sign that your cervix is starting to soften though :)
I never lost mine or if I did I never noticed with all three. Not to sound gross but it could easily drop in the toilet and you not know. Its nothing to worry about. Good luck