peeples.......Not to worry, Mom. I have one lefty (eldest) 2 righties (middle kids) and 1 ambidextrous (youngest).....In other words, at least one of each.
Speaking strictly as a "Mom".....I find it interesting that you say, "We are being told our youngest is left-handed." I assume you mean that observers (family, friends) are making this comment, based on what they witness with your child?
It's important to know how old this child is. I'd also like to suggest that you and your husband would be the best & FIRST, to notice/ judge which side your child appears to "favor."
If he/she holds her spoon, a crayon, ball, etc, in his/her left hand the majority of the time.......reaches for items with the left hand .....and/or (very important) if you notice him/her pick something up in his/her right hand, but quickly transfer it to the left, I'd feel confident to say you have a "leftie" child.
peeples.....Your question is by no means, "dumb." As a Mom "on-the-ball,' it is impressive you continually focus on all aspects of your child's needs.
Relax. There is very little, if anything "special" or out of the ordinary you will need to do, for or with your leftie, than with your righties! In fact, seeming to set him/her apart or making "too much" of the hand he/she chooses to use, may serve to confuse your child or believe there's something "wrong" with what he/she does. Your child is comfortable with being a leftie and you can be, as well.
The only thing I would like to suggest is that you read all you can on this particular topic. There are numerous books with facts, statistics and just about anything a parent may want or need to know. Anything else that may come up, you and your child will discover together and handle just fine.
One little lesson I learned when my leftie began "using a pen," in school, rather than the pencil they start out with: His list of school supplies included erasable pens. Unfortunately, these pens are not for lefties! Since their hand slides over what they write, AS THEY WRITE.....erasable pens SMEAR every word! lol.
No big deal. Good luck to a GOOD Mommy!!