Can you have a miscarriage and not know it!

Alyssa

So in 2015-2016 we were trying to get pregnant. And we got pregnant July 2016 and had a beautiful baby boy in March 2017. I am just now getting back to regular periods. And I was looking at my passed one and came across this. The 18th-23rd was in August and then on the 4th-7th September I thought I had another. And then had one on 27th of September though 7th of October 2015. What I'm asking is could the 4-7 have been a miscarriage?