MWS, I think the question here is, are you comfortable wearing a print type, or AB/DL diaper to the doctor?
If you can't get hold of good plain white diapers before your visit, you think the Attends are not good enough, and you feel okay wearing the ab diapers, then do so. You are what matters here, what is best for you, and your comfort. I'm sure if anyone sees the diapers in office, they might think "hmm?" to themselves. But in all, chances they aren't going to say anything. Not anything negative anyway. It would be unprofessional, for them to say something bad, or negative to you.
And if you have the black, well that is just an opposite reflection of a white diaper. I don't think the black diaper, is so much an AB type.
I would suggest for the future, if this is something that bothers you, that you get a package of good plain diapers. Keep this package set aside, for visits to the doctor only.