@DorsetGirl89 just endorsing the advice you have been given above. Keep a note of the spotting. With my chemical in March, the bleeding came about 5 days after my vvvfl. That chemical followed a mc I had in Feb so I hadn't been tracking for ovulation. After 2 losses back to back, my cycle was out of whack. The cycle with the chemical was 35 days, next cycle we didn't try to allow me to settle and it was 31 days. I'm now settled into a 27 day cycle. My periods have been very painful since but last month was not so bad. So my advice is to keep a note of how it progresses, if the bleeding gets no heavier the next few days and you still aren't testing positive, make an appointment with your doctor.
I think the advice that you're more fertile following a loss wrongfully builds up expectations. I'm sure that my chemical in March was because I hadn't given my body time to heal after the mc.