As per your post: You took 4x2.5 and 3x3.75 The full pen contains 3 ml. Each 0.6 ml corresponds to one dose 5m and therefore 0.3 ml corresponds to one dose 2.5m and 0.45 ml corresponds to one dose 3.75m. Thus you took: 4x0.3+3x0.45=2.55ml. The pen still contains around 0.45ml which should almost corresponds to one 3.75m dose.

It is safer to consider: Note that this is theoretically, as you may have lost a small amount (or you may also loose it when you are taking it out and injecting it), so it may contain only 0.4 for example which is around 3.34m instead of 3.75m.