Usual menses last for around 7 days but i had 3days of spotting instead of usual period. been stressed with family and career. last sex (pull out) was after my previous menses. could i be pregnant?

When in doubt: just check pregnancy test. And if you are late and first pregnancy test was negative, check it again in 1 week. If you have two negatives then you can rest assured. Then see if your periods will return to normal. If it does not in 3-4 months, you may need to visit GYN or family physician to consider other methods of regulating your periods.