Best answer by Transparent
It looks like someone@OVO hasn't re-visited your personal Home Page to bring up all the features. I think this usually happens after your first fortnight with OVO (ie once the 14-days statutory cooling off period ends).
Don't worry too much about having missed an exact date. There's always a bit of estimating going on within OVO's algorithms in the first 2 or 3 months whilst it learns your usage patterns.
I suggest you email your readings to email@example.com and make sure you give your full address so they can confirm who you are. Not only does the use of email provide you with a date-time stamp of when you sent it, but Customer Services will be goaded into enabling the rest of your online features because they will want to avoid you sending more readings by email!