Lost 10 pounds on 2.5 and only 1 in 3 weeks of 5

Title says it all. First 4 weeks I lost 10 pounds but today I am injecting the third dose of 5mg and only lost one so far. I am definitely on a deficit and feel great. Also I have near 0 side effects, while I had some on 2.5mg Anyone experienced something like this? Doctor said it's ok and increased to 7.5. It's a bit discouraging.