Blitzing and quick maneuvering is a must for Baktria. you need to take cities in a few years otherwise AS can crush you , as you may very well tell.

Solve your elephant rebel problems with some skirmishers and get the indian cities ASAP. AS won't attack you the first 3-4 years but you can bet they will come after that in full force so either you're ready to match them in numbers/money , or you die .
You should have at least 2 stacks and +5k economy to have a chance against AS and Saka.