The straining etc is pretty normal Tan, Nicholas does it alot. He also sometimes cries a bit when pooing, though I think it's more the sensation, rather than it hurting him IYKWIM? He certainly doesn't like lying in it LOL!

If her poos are normal consistency then I'd say she's not constipated, and she's just starting to go a bit longer between poos. Hooray I say!

Of course, mummy knows best, so if your worried get your MCHN or GP to check her. Or even ring the MCHN line.