beata - how slow were you going on the 10 rep workout? It seems that you're possibly somewhat close to 285 already, however, if you were going super slow on it, it's probably not as indicative of your 1rm as it otherwise would be.
My g/f seems to have a lower 1rm DL than she should (sample size of going for her 1rm once, on a day she didn't feel very strong about it) but ymmv.
My DL (1 year of barbell lifting experience) 1rm was lower than it was supposed to be and I felt I had a good pull. But last time I did bench it was spot on according to that calculator.
Anyway, I guess a summary and my main advice would be - dooo iiiiiiiiiiit!