No way you can tell just by weight. Did you see your pair mate? Both my females turned a different color when they became gravid. One female turned green to almost black, one turned orange to green. A 3rd female I purchased a couple months ago just turned from a red/orange color to green, so I am thinking she is gravid.
Not sure this time of year is the right time for laying, however, I don't have enough experience to tell you that for sure. Both my females mated this time of year and layed eggs in April. It is possible they can lay multiple clutches, however, mine did not. You can feel eggs in her if she is close to laying. If she becomes restless and wanders the cage, that is also a sign she is ready to lay. Other than that, try to leave her alone as much as possible and do as Laurie stated. good luck to you, I'm sure you'll get some eggs eventually.