Ttc and I'm 36

I lost a baby on 29th June 2015 my hcg levels where 10 so I'm guessing I was not far how long after a miscarriage can you full pregnant ...... My last period was 15/09/15 it was 3 days early very light pink and it was just when I wiped my self I only had that for 2 days blood test came back neg I don't know wants going on ... By my dates I am due 10/10/15