Could i have miscarried if i had no period sept. and one in october after unprotected sex in aug?

Possible: It is possible, but sometimes women miss a period, did you check any home pregnancy test during month of September?

Good Question!: That's a good question. A lot of unsuccessful pregnancies go un-noticed early on (I guess that means a lot of successful spontaneous abortions go un-noticed, depending on what you wanted). You might have known had you done a urine test after you missed that period in September. Did you want that pregnancy? If yes, sorry. If not, then why the H-- were you having unprotected sex?