I have a 2-bed and it is generally quite warm throughout (I have a shower almost every morning and a bath almost every night also). My monthly on E9 with EDF (same as you I believe as the pricing is the same) is generally £90 and has been around that mark for a few years (although they have lifted my direct debit to £110 for some reason which was surprising as I wasn't in debit and was actually £90 in credit!)
Your bill seems quite high in comparison. The first thing to check is whether the £130 is actually based on your spending over the past year or whether they have lifted your direct debit incorrectly (they did this to me several years ago).
If it is based on your actual use, check the meter readings are accurate – do you do yourself or does a person come round to do it? They check mine annually I believe and I send them updates every quarter or so.
Finally, on a practical point of view, on E9 it is ALL electricity is cheaper during those periods of time that it's 'cheap rate' but the storage heaters and water heater will ONLY work on the cheaper circuits unless you actively turn them on (the red light on the storage heaters and the immersion heater on the water heater).
The final thing you can really check yourself is to ensure that you do not have your water heater immersion turned on in error and that you do not have that little red light turned on at the storage heater.
Hopefully checking the above 3 things will pick up any problem you have.