Contraceptives can make you feel tired. Its most likely the combination of Yasmin
and the Trimethoprim
The way that pills work is that they trick your body into thinking it is pregnant so that you cannot get pregnant.
Many people end up feeling some symptoms of pregnancy
( including fatigue
Also Trimethoprim can cause Hemolytic anemia
( as well as many other drugs) . One of the main sysmptoms of anemia is Fatigue.
You may need to increase your iron intake.
Eat iron rich foods and see if that helps. Take supplements cook with iron skillets.
I've been anemic my whole life.