Low amniotic fluid

So since I was 14 weeks I started getting this watery discharge on and off. I went to the doctor and she said that wasn't the amniotic fluid without checking. 4 weeks later I went for another appointment with a different doc because my doc wasn't in town  and I told him about this watery discharge and again said the same thing without checking and he said the baby was fine. Baby measured right on track. But now at 24 weeks I have been having this horrible back pain and increased in watery discharge I went to the ER and they said everything was fine. This time I insisted to get my discharge checked which they did and it came back negative ( not the amniotic fluid) but the US showed an 8.3cm amniotic fluid and doctor said its normal and they are not worried unless it's less that 5cm. Well I went home and I read that it's on the lower side. I would not have worried if I didn't have this watery discharge but now Im not sure about what they told me. My heart tells me something is wrong but also I'm a worrier so I don't know what to think. Has anyone tried something that helped their amniotic fluid increase? Should I buy the PH strips to check the discharge myself at home?