Non-medically qualified data follows!
The following is an extract from the JAR Medical Standards docment:
From JAR FCL 3 Appendix 2 to Subparts B and C - Respiratory system
(See JAR–FCL 3.155, 3.160, 3.275 and 3.280)
1 Spirometric examination is required for initial Class 1 examination. An FEV1/FVC ratio less than 70% shall require evaluation by a specialist in respiratory disease. For Class 2, a pulmonary peak flow test of less than 80% of predicted normal value according to age, sex and height shall require evaluation by a specialist in respiratory diseases.
2 Applicants experiencing recurrent attacks of asthma shall be assessed as unfit.
(a) Class 1 certification may be considered by the AMS if considered stable with acceptable pulmonary function tests and medication compatible with flight safety (no systemic steroids).
(b) Class 2 certification may be considered by the AME in consultation with the AMS if considered stable with acceptable pulmonary function tests, medication compatible with flight safety (no systemic steroids), and a full report is submitted to the AMS.
This seems quite clear that your peak flow needs to be better than 70% of normal values or else you need to be assessed by a specialist. It seems like taking any form of steroidal medication is not acceptable.
Have a word with your GP / the Belgrano - I've heard of people with one-off attacks or a previous childhood history of asthma that is now resolved being granted medicals.
Good luck!