Could recent sex trigger spotting after 1.5-year period hiatus?

The effectiveness of the pill depends on factors like timing and individual variables. If you're sexually active and concerned about pregnancy, consider taking a pregnancy test if your period is significantly delayed. 

Hormonal imbalances, stress, and other factors can contribute to irregular bleeding. To help regulate your menstrual cycle, focus on a balanced diet, exercise regularly, maintain a healthy weight, and manage stress.

It's normal to have cycle length variations. Factors like stress affect cycle regularity. A 28-33 day cycle is still regular.. . See a doctor if bleeding is HEAVY or PAINFUL. 

To prevent your period from starting, you should take the blue triphasil tablet from the pack. By taking this tablet, your body is prevented from releasing the egg, which can be the reason behind the delay of your period. The scenario becomes bright when you have a special event or a trip planned, and you don't want your period to come. Triphasil is safe to use for this purpose, but you should always follow the instructions and take the pills every day at the same time.

Variant reasons can come up with missing menstruation, like stress, fluctuations in weight, or hormonal deficiencies that cause it. If you haven't had your period, try to watch for other symptoms that may have come along with it, such as headaches or mood swings. If you worry, it's better to go and talk to someone you feel secure with, such as a parent or school nurse, who can then show you what to do to be of better help to yourself.