Alternating charge

Im wondering if my aternator is telling me something.When I run my heat due to cold mornings when I get off of work,it usually will stay at mid or a little lower,then when I roll down my windows while blower is on it goes down to like 9-10 amps and lights dim down quit a bit,is this normal or should I have it checked out and my battery is 550 cca it came with it when I bought it.I think it sucks.

check the battery connections first and the alt wire connections.

and if they are good, then it would be ur alt.