The food item should cause a very slight bulge in the snake right after eating but shouldn't be as visible the next day and gone within a few days. You should be able to start feeding weaned mice at around the 100-120 gram range and move up to small adult mice shortly after that. Regurgitation can be an indicator that you're feeding too large of a prey item but it can also be an indicator that your hot spot is too cool or that the snake is overly stressed out. As long as your snake continues growing at a steady rate you're doing it right.