Travel and Periods

So just over two months ago I had sex and haven’t since. Now he didn’t cum and he wore a condom. I got my period on time 4 days later and then around 29 days later I got my next period. I’ve been travelling around Europe for just coming up to a month now and my period is currently 9 days late. Since I got my last two periods on time and he didn’t come and was wearing a condom, I shouldn’t be worried about being pregnant but I am curious if anyone has been in a similar situation? I have never skipped a period or had a late period so I am new to this. And my next period is due around the time I fly home (6hr flight & 14hr flight) which will once again have an affect on me and most likely my cycle. So if my period doesn’t come this month snd then again doesn’t come next month for the same reasons, should I be worried?