2 missed periods help!

Hello.

I am 16 years old I started my period early this year in February and I am currently travelling in japan. I arrived in japan is late august and I missed my period for that month. On day 43 of this cycle I had 3 days of red/brown spotting. And now its almost the end of September and still no period. I am still currently overseas and will be until early October.

Is the 2 missed periods due to travelling, and why did I spot on day 43 of my cycle? Im currently on day 62 of my cycle. Ive also had 2 missed periods in a row before the month after i first started it.

I also did take a pregnancy test the day before i got on the plane And 14 days after sex. And it was negative.

Thanks.