Unknown wiring schematic deduction for outlet
You should be just fine as far black/hot vs. white/neutral.
However, you may or may not realize how the GFCI is wired. With an ordinary receptacle, it doesn't matter whether a wire goes to top screw, top backstab, bottom screw or bottom backstab. With GFCI, there are two totally different sets of screws - LINE and LOAD. To avoid problems, the LOAD screws are normally covered with tape to prevent accidental use.
By pigtailing everything together, you have everything on LINE. That is perfectly OK, but it means that any downstream receptacles are not protected. If you expect (or want) downstream receptacles to be protected, then a little more work is needed.