Hello
Composing a leak, no matter how small, is no small feat. Especially if we start to do without knowing well. By ear it will not come out for sure.
You see, whether the response to the subject is tonal or real, is not a choice. There are certain things that condition one or the other, so that it works.
To write a real answer (with all the intervals exactly the same in the subject and in the counter-subject), the subject must start on the tonic and end on the tonic (C, in this case).
When the subject has the dominant note (G) preponderant, either because it appears at the beginning or because it appears by leap, the answer has to be tonal. And tonal means that sometimes the intervals have to be changed to bring the notes back to the tonic.
Anyway, this is long to explain here, but that's the way it is, otherwise it doesn't work well.
On the other hand, the subject has a very irregular thing in the melody design. In measure 2 there is a melodic scale that ends in the sensitive (G-A-B-E).... This should resolve to C. But even stranger is that it jumps from B natural to F natural (tritone jump, in strong position).