Absolutely not. However it’s important to get to the bottom of why you aren’t having a normal cycle.
Rapid weight loss and change in activity can be a factor sure. As can stressing about it.
However at 7 months you are starting to push the limits of a amenorrhea to the extent where it may be beneficial to see a doctor for an exam and blood work.
Even if you’ve already gone. If your appointment was earlier than 90 days or so it may be time to follow up for a second look.
If weight loss pushes your body fat below a certain level, your periods can stop. (The body thinks it is starving, so does not ovulate. No ovulation = no period.) You don't mention your weight -- this is not a problem for someone who is merely going from voluptuous to average, or average to slightly slimmer, it relates to someone edging into anorexia territory.
You also don't mention your age. If you're around 50, periods stopping is a different issue than if you're around 20.