Even your reasonable assessment that BD army is for defense purpose is not valid. In a modern war, the air force planes are the main attack force that also supports the ground troops. BAF lacks strength without sufficient number of planes.
BA or BN is incapable to resist MM air force attacks in liaison with its simultaneous missile attacks. The BA/ BAF even lacks enough number of short, medium and long range missiles to protect the country's sky and land from the MAF plane attacks.
A war is not fought and cannot be won by only a little strategic philosophy and bravery. It must be supported by adequate number of all kinds of weapons most importantly adequate number of fighter planes.
The country's military is unable to conduct also a defensive war. Myanmar's Iskander M missiles can reach 500 km maximum. It means, it can hit Cox's Bazaar, Chittagong, Dhaka, Paira as well as Saidpur/Panchgor in the very north when fired from the MM soil.
So, how BD can protect itself even in a defensive war? I ask our talented strategists in the PDF how they propose to wage war from such a weak position?