You should feed a prey item that is about 1.5 times the width of the snake. When I first got my '05 hatchlings, I fed them one pinkie mouse each. I would look at them after 24 hours, and then again after 48 hours (total from the feed time) to see if there was still a sizable lump. You should see a lump at least 24 hours after a feed.
When I no longer saw a lump after 24 hours, I fed 2 pinkies to each snake. I did that for 5 feedings and then moved to one fuzzy for each snake (making sure that the fuzzies were not bigger than one-and-a-half times the girth of the snake.
You can actually hold the mouse up to the widest part of the snake to sort of eyeball it. The next step after fuzzy is hopper, and then adult. I can't find hoopers around here, so I will have to move right to adults.
Did the man feed her all 3 at the same time? This seems like an awful lot. IMO, you should move up to fuzzies right away if she is eating 3 pinkies at a time. Older mice offer more nurishment than their younger counterparts.
Yikes! I just realized that you said 45cm. One of my snakes is 57 cm, and the other is 52 cm. Both are on fuzzies and about to be upgraded again. Hopefully, this will help you make a decision.