I was under the impression that my social security benefit would be automatically adjusted to be half my husband's. Would the fact that l took mine a year early affect that, or did l misunderstand?
Yes, if you start drawing your own Social Security retirement benefits before full retirement age (FRA) you're stuck with the resulting rate reduction even if you later become entitled to an additional spousal benefit.
For example, say Jane starts drawing her retirement benefits at age 64. Jane's full retirement age rate, or primary insurance amount (PIA), would be $1000, but she receives a reduced rate of $866. Jane's husband files for his benefits after Jane reaches FRA, and his PIA is $2500. Jane's unreduced spousal benefit would be calculated by subtracting her PIA from 50% of her husband's PIA, which in this case would amount to $250 (i.e. $2500/2 - $1000). That partial spousal benefit would then be added to Jane's reduced retirement rate of $866 to give her a combined benefit amount of $1116.