It does sound like she might be getting ready to lay eggs.
If you wanted to prevent egg laying, you could take her to the vet and ask about a lupron injection. The vet will probably feel to see if there are eggs developing in her; if there are eggs, it's probably too late for the lupron though. And the lupron kind of works by overloading her body with hormones and generally isn't a permanent solution to egg laying.
Egg laying really isn't all that dangerous though. It can be a little riskier in pet birds than in wild or aviary birds, just because pet birds tend to not fly as much and the flight muscles aid in pushing the egg out. But the overall risk is low and laying a clutch of eggs a year really isn't likely to cause any problems in a strong, healthy bird. Problems are more likely to occur if she's weak or unhealthy, or if she becomes a chronic egg layer and lays many more eggs than normal (which would be unusual for an amazon).
Make sure she gets a healthy diet, at least 2 sources of calcium -such as mineral block, oyster shell, eggshell, cuttlebone, even Tums (most other human calcium supplements contain zinc so be careful). She might also need some vitamin D3 if she doesn't get some natural sunlight or pellets with D3 added.
Once she lays, let her sit on her egg. I might try placing a shallow cardboard box, tray or something similar on the bottom of her cage with a little paper in it to shred, if you are fairly confident she will lay. As a general rule, you don't want to offer nesting materials since they can encourage egg laying, but once she's already going to lay, she needs somewhere where she can comfortably sit on the eggs. This is key - if you take away her egg, or if she breaks it on the cage grate, she will lay another to replace it, and could eventually lay more than is healthy for her. She needs to be allowed to sit on her eggs if she is interested. Giving her a safe place to lay eggs will also make egg binding much less likely.
