I'm so sorry for your loss! The only other thing is that I've heard sometimes of bugs biting the tortoise when they're outside? I don't know where you are, but a few have mentioned fire ants. But, I think that what that person said about the tortoise possibly being a lot older could be very...
Thank you for your story! What I’m taking from what you went through is try everything you can for as long as you can. We have two Indian stars and thought they were both male but then they laid an eggs two weeks ago!
Just make sure that one side of the enclosure is cooler so she can cool down if and when needed. And make sure the substrate is damp and humidity is high enough.