Tender breasts but hcg not zero yet?

Trying to figure what’s going on with my body..my hcg was 16 two weeks in a row (after 3 months of it going down steadily and a ipass to suction retained products 2 weeks ago. Now my breasts are tender like I’m about to get my period. Has anyone gotten their true period with very low levels of hcg? Did that help get it down to zero? Not going for another draw until Wednesday...