Do I Share My AT&T Data Usage With My Family?

So my mom just sent me a text saying that I wen't over my 3G AT&T cellular data usage. Now, thats IMPOSSIBLE because as soon as I got a message saying I used 90% of my data, I wen't to my phone settings, and disabled cellular data; from that point on, I didn't go on the internet unless I was over Wi-Fi (the iPhone5s wouldn't let me, which is good). I was curious, could my mom have gone on the internet over 3G with our possibly SHARED data plan? Like, just for an example, I use 50% of my data, then she uses 20%, then my Dad uses 25%, then my Mom uses 5%, even after I get a message saying that I'm 90% over the usage, and I disable cellular data? Please tell me, thanks.

If it wasn't you it must be someone else on the same plan. All minutes/data are all shared with everyone whom is on the plan.

Ask your mom. Our family plan had us each able to use 300mb, now we're lumped together with 1G shared by 2 tablets and 3 smart phones.