Am I still using cellular data with Wi-Fi on?

So, my dad recently switched to Verizon from t-mobile and it's really been annoying. We haven't even been with Verizon for a month and I already hate it. Back with t-mobile, we had unlimited data, and now we don't. In the first week or so, I alone used 75% of the 10GB data plan we have for 4 people. Learning this, I turned off my cellular data completely (I even turned it off for every individual app) and switched to pure Wi-Fi. I have the iPhone 5, so it tells me how much I've used and the number hasn't moved from 6.9 GB ever since I turned off my cellular data. However, my family is still receiving texts from Verizon saying we're going over data usage. I don't know who is doing it, but I just want to make sure that it's not me. With my cellular data off and Wi-Fi on, am I still using my data allowance? (Please note that the Wi-Fi I use isn't from Verizon, it's from the motel my family and I are currently residing at).

From what you've said you're not going to use Cellular Data when you're connected to your Wi-Fi network; however depending on what you've used to restrict the Cellular Data it may switch to it if a Wi-Fi network is not available to connect to. Due to what you've said with the data not moving though I think it's safe to say you're not responsible for going over the limit.

What you and the family need to do, is all download the same Data Monitoring app, set it up to match your billing dates, and have it monitor BOTH Cellular data and Wi-Fi, so that it shows which of the phones are using cellular data and how much and at what times.

Another thing to check, is to make sure the phones are not doing backups of pictures and videos unless on Wi-Fi, and no audio or video streaming for the family, unless on Wi-Fi, would be a pretty good rule if you all near Wi-Fi most of the time.

If Wi-Fi is available then no, if not, yes.

You turned it off, but did the other 3 people did?

Shutting off cell data stops all cell data use, but other members of your family may still be using cell data. If you avoid streaming video, my hat lone can dramatically reduce your cell data use even if you leave it on for other things.

Even wth four people using the account, if none of them watches video, you should still be around 3-4 GB per month, not 7.5 GB in a week.