there is nothing Wrong with the LC9 for a sub compact especially if you have the LC9s pro that removes the magazine disconnect
I carry the original LC9 the double action the LC9s is striker fired
it sounds like you need holsters , the thing about holsters is everyone gets a few , I make my own so I have even more
we could talk about larger guns I like my Glock 19 for it's capacity but I think NY limits you to 10 rounds or less any way
9mm is a good choice it brings nearly the power of any other handgun but in a less expensive to buy round for practice
all good carry ammo is hovering around a dollar a round in most cases
modes of carry you can do with a LC9 , I pocket carry it in a Alabama holster company Kydex pocket holster , you can carry IWB in the wast band , an Ailien gear is a good but not bank breaking option for this or you can carry OWB outside the waste band
the Belt should not be overlooked , you need a good belt even the light 17.1 oz gun with 4-5 more ounces of ammo hanging on a belt all day will make a poor quality belt sag or twist. the belt needs to hold it's shape with weight on it especially if your going to run a pancake style OWB with a high center of gravity. this holds the gun up high and makes cover garments more easily conceal the gun .
time to ask yourself some questions ,
Am I putting this gun on and wearing it all day every where I go ?
or do I need to be able to take it off and secure it soem places I go ?
if you answered that you will need to take the gun off you may want to use a paddle type holster
the last thing I want to do is have a Negligent Discharge when I am out and have to take my gun off and put it back on SO I never remove it from the holster if I don't have to , I take it off with the holster , if I am in and out a lot pocket carry the holster comes right out of the pocket stays with the gun and I can secure both , or OWB with a paddle
for training purposes I recomend an OWB your going to be in and out of the holster , make it one that is easy to holster , ridged be it leather or kydex the gun should move with you and not bounce around
her is a Kydex pancake pancake means it is 2 peices of Kydex sandwich molded around the gun , I cut belt slots in this one but it could have belt slides that secure with screws also
the gun goes in an out easy enough for me but is held firmly enough that if the holster is turned upside down and given a shake the gun will not come out. at minimum it should not come out when turned upside down, you shoudl have to overcome the tension holding it in to draw.
this slight leaning forward angle is called FBI cant because the fbi figured out when your sitting in a car or at a desk you get poked less in the side if it is tipped forward a bit
the LC9 is thin it hides easily with an undershirt / tank top and a slightly oversize cover garment be it a t-shirt or button up shirt left untucked
I like the Duluth Trading long tail T's because I am already tall and most t-shirts would show my belly but ideally I can raise my arms over my head to reach a high shelf at the grocery and not lift my shirt above the bottom edge of my holster I like it if raising my hands over my head my shirt still covers all + an inch or two of the holster.
start with an OWB because you will need it for training , it is January and that gives you time to get other deeper concealment options later as things warm up.
next thing you need more magazines , 3 is a minimum for training more is better , stuffing mags is wasting instructor time
a mag carrier for the weak hand is ideal especially if your instructor will have you running move and reload drills
practice up shooting basic target first , figure out your trigger control , work on shooing an accurate group on target at say 20 feet the LC9 is easily capable of a better than 6 inch group at 21 feet but get to where you can shoot a 6 inch group at 21 feet , dry fire can be very usefull in this , concentrate ont he front sight on the target and sqweeeeeeeeze keep your sight on target , repeat , repeat , repeat till the gun is on target all through your trigger pull and the click. then laod up and repeat till you have the group
holster and un-holster dry a bunch of times as in no ammo
finger off the trigger till the sights are on the target
practice that as soon as your gun clears holster your muzzle moves forward and your elbow down , this is not the greatest video but basically explains retention , I don't worry about the ejection port pointing out , just pull gun out elbow down muzzle toward target , you can shoot from that position or you can continue right up into a 2 handed grip and push out to shoot.https://www.youtube.com/watch?v=nqQAgtNMwDY
this guy re-holsters fast , no need to re-holster fast , do it slow , deliberate make sure no clothing is getting in the way and you are not pointing the gun at yourself finger is of course off the trigger , if the police show up and you haven't re-holstered yet no worries before they get out of the car lay the gun on the ground put your hands up it is much more likely you will have to call the police and wait for them to show up, look around you with gun at low ready , when the area is safe re-holster