'pressure in uterus' could be many things because location is midline pelvic in origin.
Of course you can take a home pregnancy test if you are more than 1 week late on period (should be postive by then). A bladder infection (UTI) or bowel problem such as constipation can cause 'pelvic pressure', too.
Severe right lower abdomen pain could be appendicitis or ovary problem. Hope you are better.
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