1382 kWh * 3 (to get 12 months) is 4146 kWh per year, which isn't bad considering you're only using electric. But then you have to remember those readings are from a time of year when usage is starting to creep up, due to lights being on longer and increasing demand for heating towards winter.
I have a spreadsheet with EDF's Standard Variable tariff and with 4146 kWh and it tells me that's nearly £80/pcm. As
@200sols says, £90 would be a good amount to set your direct debit to.
Have you just moved to Bulb? If so, perhaps they will just need to see your usage over a longer period, before their calculations will give you a more realistic figure to set your direct debit to. Ride it out and pay what they ask. If you're right, you might be in for a refund in the middle of summer.