If you had a video of her behavior - trying to get inside after going to the bathroom - that might be helpful to gauge if it really is fear.
That said, I think there was some great advice from
@Rain and
@Shandula on your other thread. I would work with her on being outside even when you don't absolutely need her to go out there (so in between potty breaks). Start treating just for being next to the door, then with the door open, then for sniffing the air outside or listening to noises outdoors, then for sticking a head out, then a foot -- basically any willing interaction with the outdoors gets her a really, really good treat.
After that you can start putting treats on the porch outside, then maybe a trail down to the steps, etc. Obviously she'll still need to go out for potty breaks, so until she'll happily walk outside either carry her out and then in when she's finished, or try having her walk with you and treat her for
every step she takes.
Once she's able to better be in the yard, that's the point where you can start making the yard a really fun, habitable place. I think
@Redwood had a good idea on your other thread - you can move her stuff out there and hang out with her, again constantly rewarding and playing games. But I wouldn't move to this until she'll eagerly go outside, and at any sign of fear or uncertainty I'd get her back inside ASAP.
And...once you're able to get her to be happy in your yard, you can employ the same techniques (delicious treats for baby, baby steps) to get her onto the sidewalk, down the block, etc.
I know you've said you were short on funds, but I'd start seeing if you can save even $5 per week toward a trainer/behaviorist. Even an online one via skype would be helpful. Bella's had some fear issues I know, as does my dog, but a dog that won't go out into their own yard due to fear is probably one that needs professional help.
For now though, baby steps, keep it all suuuuuper positive (work on your happy voice!!), and don't push her more than she's ready. Even if she seems okay, play it safe and take things a step back to be absolutely sure.