Thanks for the query.
Scanty flow during periods can occur due to many causes like hormonal
And also just by symptoms we cannot confirm or rule out the pregnancy
The symptoms you are experiencing can also be due to hormonal effect as part of routine menstrual cycle.
So you better go for blood test
for pregnancy once. If the test comes negative, you can take symptomatic treatment for current symptoms.
If the symptoms persist or become severe you better consult gynecologist and get investigated to find out the actual cause of the problem.