Hi, and thanks for your medical question on eHealth forum!
Yes, I agree, asthma can be very debilitating. However, the good news is that it can be easily kept under control. With proper medication which will have to be tried and see, which combination helps, symptoms will be well under control and you can try for pregnancy.
Common Allergens are dust, pollen, animal dander, perfume and spray. You can yourself try and spot what causes you to have more symptoms. Please consult a chest specialist for proper evaluation and treatment. Hope this helps. Take care!