I have gone through your query and understood your concerns. The chance for pregnancy
is less as you have got negative results but I suggest you to repeat the test after a week. As you have mentioned that you got cyst
earlier so that may be the cause for your delayed periods. take iron tablets as if your periods are delayed due to anemia
then you will get your periods after taking iron tablets. About brown discharge some people will experience such type of discharge before getting periods. Thank you.