Why do I use so much data?

I've owned my BlackBerry Keyone for around 10 days now, I love it! I have been a long time IOS user and have never used Android before.

I've upgraded from an iPhone 6, I had a 5GB data tariff which sufficed. I have now slightly upgraded to a 6GB Monthly data tariff.

My data allowance resets on the 20th of each month, it is the 22nd of the month and I have used 3GB meaning I have 3GB left! According to my "MY 02" app.

How have I used 3GB of data in 2 days? How will I survive with no data for 3 weeks of the month?

My iPhone never used this much data!

Have you got any tricks/advice on why my Keyone is eating so much data and how does this Android newbie resolve it?

Thank you.

Also: How much data does the average Keyone owner have?

Can you post a pic of your data usage: settings, data usage: