Don't be too worried if the jam seems to be thinner than you would like, because it will become much thicker as it cools and sets. As long as you cooked it long enough and it reached 220 degrees Fahrenheit, it should be ok. However, if the jam is watery and too thin even after cooking it for more than an hour, continue cooking it. It's possible that the heat was too low or your pot wasn't wide enough, so the jam wasn't able to thicken enough.