I lived in an 1100 sq ft house with radiators and a boiler from the 80s until last year, and it was about 150 a month in the winter. I didn't run it 24 hrs. But I kept it at 68-69, so 245 for 15 days seems high. Try to turn it down when you're sleeping or not home. Maybe try bleeding the radiators? 5 years ago I lived in a 700 sq ft house with radiators and 0 insulation, and it was about the same price. I bought those plastic sheets to put over the window to reduce the draft, which worked reasonably well.

There's also plans with PGW to make your bill more consistent throughout the year rather than spikes in the winter. Of course, the downside is you're paying for it in the summer when you're not using it.