Okay, so, you should be able to calculate the dose if you know the thc content (average will do, so try the strain info with the manufacturer) I'll tell you how to do that later on. Problem is, what's a safe medical dose for beginners?
What I've read is that in Colorado by law, edibles can have dosages that start at 10 milligram per gram with increments of 10 milligrams per gram, always. This suggests that 10 milligram is a starters dosage. For safety reasons it might be best to take half of that. So what you want is give her 5 milligram of THC.
If anyone thinks it should be a different dosage, please feel free to correct me.
Now you know you want 5 milligram of THC in the tea and you know the amount of THC in the buds - let's say it's 15% - you can start calculating.
Every gram of bud contains 15% THC. One gram equals 1000 milligram. This means, if you were able to get all the THC out, that would be 150 milligram of pure THC from one gram. Let's say you get it all. You only need 5 milligram in the cup. So using 1 gram of weed would be far too much. 150 milligram is 30x5 milligram. You'll only need 1/30th of a gram dried bud. That's 33 milligram of dried bud.
To be honest, I have no idea if the extraction method you use will get all of the THC out. I guess, the longer you soak, the more you'll get out of it, providing you added enough fat to dissolve the THC in.
From the picture I've seen, you're soaking more than 33 milligram of dried bud. EDIT: I just reread your post and see you're using a full gram...be aware that if she drinks the whole 1,5 cup, she might be as happy as I will feel after I've had my next spliff!