First of all, usually it's not the army to assist the border guard in "neutralizing initial (invading) forces", but the other way round: border guard assists the army. Even the most "heavy" border guard forces, like East German Grenztruppen or parts of the Soviet Pogranichnye Voyska deployed in some parts of the far-eastern border with China after the 1969 Ussuri clashes (which even had 122mm howitzers) weren't supposed to do much more in case of the full-scale invasion than do a phone-call to the HQ and last on their position for several hours, slightly delaying the invaders and allowing the army to start mobilization. Border Guards are about stopping "incursions" and "infiltrations" rather than "invasions".
Secondly, "continually falling back" in itself contradicts both "maintaining morale" and "maintaining strategic dominance". "Falling back" is never too good for morale. Finnish army of the Winter War wasn't supposed to "fall back" any more than to the Mannerheim line in the south, and in the north (which lacked the of more-or-less continuous front line anyway) emphasis was more on channeling invading forces into narrow areas and attacking them from flanks and behind, which is not the same as "continually falling back" (term impicitly suggesting "trading space for time" done by the Soviets in 1941-1942). More importantly, "falling back" means that it's the enemy keeps strategic initiative and therefore dominance, by choosing where and when he'll attack. There's totally nothing "dominant" in "falling back to avioid casualties". It's what French Army did in June 1940. :>
Thirdly, population of 18 million people is not really that small. It's more than 3 times population of Finland, nearly twice the population of Sweden, or half of the population of Poland or Canada. It's accepted as a rule of thumb, that a country (at least with something resembling working economy) can keep a peacetime military establishment of 1% of population (which is 180.000 in this case) before it becomes too much strain of economy. Of course equipping such amount of people with modern equipment is sometimes different matter (though in developed countries these days it's mostly about political will and spending priorities rather than some inherent impossibility), but with a peacetime military of nearly 200 thousand (with possible war-time strength in million-range) once can do much more than just rely on allies to come for help, especially when the landscape gives you such bonus in defence.
As for the organizational sheet... :/
One thing is that it's arrangement is rather confusing because the lines showing subordination go through HQ units. So the way it's now, it suggests, that Mech. Infantry Bn is composed of single
Headquarters and Medical Co., and that HQ/Med.Co. is in turn sub-divided into
-Battalion Headquarters Company,
-Headquarters Company Headquarters (WTF?),
-three Mechanized Infantry Companies.
I suggest You rather make it like that:
-this way the lines are shown as coming between higher and lower units, rather than through HQ elements - it's implied (but clear) that these sub-units are led by their commanders anyway.
Next, I see over-abundance of drones there - both in Scouts Platoon and company Intel Teams. You copied it from somewhere? IMHO it's enough to keep these in Scouts Platoon. Area covered by a battalion isn't really that large, even in Finland/Canada-esque country and they just wouldn't really encounter that many targets to watch - besides, I assume there are some higher-level units that would have larger drones that would give "bigger picture" anyway.
What I see very conspicuously missing from that battalion is lack of any mortars, and the "heavy weapons" in the Heavy Weapons Platoons aren't really that heavy be it in quality or quantity. Typically a battalion has 6-9 mortars of 81mm-82mm calibre - sometimes even 4-6 (occasionaly more) 120mm mortars on battalion level and 2-3 81-82mm mortars in each company (of course all of them either towed by a jeep or on an armored vehicle). Many armies also have 60mm mortars in platoons, but that's usually seen in the light infantry units (though I believe that British Army until relatively recently had 51mm mortars in it's "armored infantry" battalions too). As for the other "heavy weapons" - keep in mind that more often that not such weapons as machine guns, anti-tank missile launcher (btw. You don't seem to have too many of these too - I assume that each of the Infantry Fighting Vehicles has a launcher, or otherwise this battalion is very soft on anti-tank defence), smaller recoilless guns (like Carl Gustav) etc. (basically anything that's not disposable after single shot) has a crew of two
- one is carrying the gun/launcher (and operates it), second is carrying ammunition/spare missiles/projectiles.
In relation to heavy (or maybe rather heavy-ish) weapons, there's also something in the platoon organization. First of all, usually Mechanized Infantry platoons have up to 4 IFV's - 3 for basic rifle squads and 1 that carries platoon "HQ" (which is much more miniscule than in Your sheet) and
platoon support weapons. Typically "platoon HQ" is just commander (lieutenant) and assistant (sergeant). Maybe add to this someone carrying a radio (arguable in Mech.Infantry). Driver is together with support weapons element, and there are no gunners in HQ.
(though at least in the past Israeli mech.infantry battalions had
6-men command squads, but they weren't armed with anything heavier than UZI)
As for the squads, with mech.infantry, they tend to have CO, driver and either 2 (or more) identical teams (with, say 3 rifles and 1 LMG) or 1+ "light" team (rifles only) and 1 "heavy" team (MG and/or some other heavier weapons - anti-tank launchers, light mortars etc.).
Btw. large part of the personnel, incl. officers, rear-area personnel, drivers etc. would be rather armed with pistols or sub-machine guns rather than full-length rifles, which tend to be too cumbersome for the tasks they do.