She's probably comfortable... its you that will be un-comfortable...lol. If she hasnt started bleeding yet, other ways to tell are her if her "nipples" and or "private area's" are swollen? If so, than you can expect a "flow" to occur in a few days.
I kinda let Meka do her thing when she's in heat. Meaning, I dont put a diaper on her unless we are going somewhere. I like to let her be able to clean herself and feel comfy when we're at home. Though, I dont allow her to roam freely during this time because it limits any mess... Hope this helps
Also, Meka's has lasted anywhere from 2 to 3 weeks... And the disposable diapers you get from the stores dont work. Ive always had to cut and tape just to make them fit Meka. You might want to look into the many vendors on here that make "panties/diapers"