Hello and welcome to e health forum.
The presence of a chronic renal disease like Good pastures syndrome, with reduced renal function (of 75%), it would be a difficult situation and there would be chances of worsening of your condition during pregnancy.
If a patient with Goodpasture's syndrome becomes pregnant, she might develop hypertension and the fetus may develop intrauterine growth restriction requiring premature delivery. Both mother and baby will be at risk.
The normal range of creatinine for women is 0.6-1.2 mg/dL. Your levels seems to be elevated.
You might consult your nephrologist who can assess your ability to tolerate pregnancy without any adverse effects before you go ahead and concieve. Your doctor might help you prepare for the pregnancy in a better way, in case, it can be allowed.
I hope this helps.