It sounds like you're having a rough time with this. I'll try to help, okay?
First, there are some pieces missing to this puzzle. What were you treated with? Did the doctor prescribe Flagyl? Did you have sex with your partner AT ANY TIME during or after the treatment? I'm asking this because you could have gotten it back immediately after being treated. You did mention you're no longer with this partner but I'm not clear if you were immediately after treatment. If so, was he treated, too?
As for the amount of discharge that's normal, it's difficult to explain. Some women have more than others. However, the thing to look for is whether or not it is tinged with blood (a symptom of trichomoniasis), green or yellow in color and/or malodorous. If any of these apply, it would be wise to see your doctor again. It's always possible that she diagnosed trich but missed one of the bacterial infections (chlamydia, gonnorhea) which are treated with antibiotics and not Flagyl.
Let me know if I can help you further!