Period no longer a year abroad?

Hello, I've been in Africa for a year abroad for three months now. I haven't had my period since I've been here. So, it's been almost three months now.
At home, too, she was often irregular, but never for more than 20 days.
Pregnancy is ruled out.
I've also been taking malaria prophylaxis since my stay here. Could that have an effect?

It's probably just the stress, but it still worries me. Do you think these concerns are justified and should I take any action, especially since I'll be here for another six months?

Thanks in advance 🙂