It's often difficult in my urban suburb to find lemongrass. Unless it's a main flavor, I generally omit. You have great ingredients for a Thai or Indian curry or just a curry. It'll be delicious. It's great to cook and improvise.

It sounds delicious to me, lemongrass or not!

You could use lemon zest or preserved lemons in place of the lemon grass.

Cilantro or just use what you have. Most of my Asian recipes do not use the lemon grass. that is the fun part of cooking...experimenting