when ever you go and look at guns, before you go, do some looking at shotgun HOLD form when shooting, learn what cheek weld is, how the stocks fits on your face when your holding it in a shooting position, how the butt of the stock fits in your shoulder pocket, and HOW far away the pistol grip is and then your fingers are to things like trigger and safety
this area is one of my BIG grips about youth guns and guns for females(smaller hands and arms)
most all makers just take FULL sized guns and then trim rear(butt) of stocks to make them shorter, which does NOTHING for those with smaller hands and fingers to reach trigger and safety's
so pay attention there
ALSO< and this is also very important to pay attention to when actually shooting shotgun(again remember form , so you don't punch yourself in the nose with recoil LOL)
and also,
PAY close attention to what type of shells they let you shoot, and by this I mean length of shell(as in 2-3/4,3 inch, or 3.5 and GOD I hope no one lets you shoot a 3.5 here, save that for when your more seasoned shooter IF you wish to try that) and then pay attention to the shot size and charge, as pending what shot and charge the round has, can factor in a LOT as to the recoil it will send back to the shooter
a semi will be a WAY better gun for you, and its due to lots of reasons, , one less recoil, two, your shorter arms will make reloading harder on you, causing you to break form a LOT more, which will make you more likely to miss on second and third shots
makes just shouldering gun harder as you don't have as many options for hand placement as a semi will offer you
so honestly, a semi is your better option here ( I sold over 17,000 guns over the yrs when I had a gun shop so I have a little experience here not to mention all the yrs I been shooting and training shooters)
old saying buy one cry once! some times better to spend a little more and get ONE gun that fits you and works best for you, you will be more accurate , hit/kill more things, find more success and that will make you more likely to want to stick with the sport
buying a gun that doesn;t fit you, makes you miss more than hit, will make you NOT enjoy shooting it or staying with the sport
NOTHING wrong with 90% of all used shotguns to help you save money here too, just have it gone over by a GOOD gun smith, almost every wear part is replaceable and NOT that costly
LAST< since you are planning to hunt waterfowl, MAKE sure what ever gun you get is set up to handle steel shot(has to have a certain choke in the barrel(more important on used guns with FIXED chokes) few modern shotguns DON"T have replaceable chokes these days, but you still need to have the correct choke in the barrel for steel shot, when shooting steel shot out of it, or can cause damage or worse
IF you stated what state and or like area here you might get some better info on gun shop recommendations to go to, or maybe even some offers to help you get started, never know. just saying!