I kept stick insects for a couple of years before i moved to the US and had to give them away. Your 5" ones may well be laying eggs already, they usually have 6 moults (I think) before being fully grown and starting to lay eggs. Their eggs are tiny, so be warned, they look like small brown seeds with a lighter coloured 'cap' at one end, which is where the baby will emerge. They look different enough to their poop that you can see the eggs when you look for them, but similar enough that if you weren't looking for eggs, you'd probably throw them out with the poop. I had 2 adults and ended up with a few hundred eggs, they seemed to lay around 20 per week, some of which wouldn't hatch because they'd been in a damp patch or similar.
An interesting thing to note is that 99% of Indian stick insects are female and require no fertilisation of their eggs, so will produce clones of themselves. The 1% of stick insects that are male are almost always infertile.
If you've kept them well this long, you're doing a good job! Mine thrived on privet, which I used to pinch from a neighbour's hedge on my way home from dropping my children off at school!