Hydrometers are dirt cheap and a critical tool (refractometers can take over for OG readings, but many still rely on brewing hydrometers)... GET ONE right away, before you brew/make ANYTHING else...
OG readings are very important. A lot of other steps depend on knowing at least that, plus where the gravity is currently. Since you have no idea what the OG was, you really can only wait and see. GET a hydrometer and take a reading in a couple of weeks to see where it is. If you get one within a day, or two tops, then you will at least have an idea of where things are at that point. But, there's almost no way to know what the OG was at this point.
It's like driving without a gas gauge or any odometers. You'll never know when you'll run out of gas.