Periods after miscarriage

L
Hi ladies
I've posted something similar to this before but I need to update it as I'm so desperate for advice now! Sorry if this has TMI.
I had a miscarriage at 5 weeks on 5th November and since then I've had cycles ranging from 25-38 days, I've had loads of watery pink spotting between my periods and in the middle of every cycle I've had between 2&5 days of thick brown or dark red discharge which is also just like spotting.
I'm at my wits end with it now! I feel like I'm never going to get pregnant again!
I'm on day 30 of my current cycle and I've had a dull cramp, especially on my right hand side every day of the whole cycle, I've had my usual brown and red discharge that lasted five days and I'm now having my usual watery pink fluid. My boobs have been killing me for the past 4 days but 2 pregnancy tests have come back negative.
Does anyone know why my body is having all this spotting and cramping?! I can't cope anymore! My GP is being zero help and keeps telling me to "wait and see how it goes"!!