Yes, if you suspect that you may be pregnant and cannot distinguish between PMS and pregnancy symptoms due to the similarity between them, you can take a pregnancy test to clear your doubts.
The fact that you have your period does not interfere with the accuracy of pregnancy tests. Keep in mind that pregnancy tests do not use estrogen to determine whether you are pregnant or not, but they measure the amount of hCG in your urine, which does not vary even if you take the test while on period.