First of all you must decide which is more important, having a cat or having your health.
Best to keep the cat outside most of the time, limiting time in the house and only in a certain area. Keep that area cleane and vacumn every day. Wear a mask all the time.
My little granRABon at birth was allergic to their cat and finally had to get rid of the cat. Took a while to determine the cause of the rapid, difficult breathing. It was terrifying taking care of a newborn with such breathing problems, all because of a cat.
Cat hair and flakes from skin become irabedded in furniture and very difficult to remove completely.
Taking Zyrtec will help some, however, the long term daily use might not be the best for your health either.
I always had cats, but, they lived outside and I lived inside.