After the veset days have been observed, there is no further halachic requirement to perform bedikot or to abstain from relations.
Sometimes periods arrive late and sometimes a woman skips a cycle. You should use your best judgment in deciding how to proceed.
If you are concerned that your period is imminent, you could choose check yourself before relations by wiping externally with toilet paper, not immediately after urinating. If you find blood, you would not have relations but also would not be niddah (until you get your period). On the other hand, if you choose to do an internal bedikah and find blood, you would be niddah even if it turns out to be only spotting and not a period.
Please feel free to get back to us with any further questions.