I think the Zyrtec has helped Claire. Her symptoms started when she was four months old. We live in a town that is horrible for allergies. (Lexington, Ky) She had a runny nose and watery eyes for about 3 months in the spring and early summer and then is went away. The doc said it could be allergies but that they generally don't test for those things until after a year. Well, when spring came around this year, we began seeing what I lovingly call, the "perma tear, again. We had a scary allergic reaction which turned out to be tree nuts but in testing we discovered that she was allergic to pollen, grass, dander, etc...
The allergy testing is not fun. I would wait till a year to have it done, as I have heard it is less accurate before then. In the mean time, note when the symptoms appear. Are they after being outside, crawling on the carpet, or around pets? Just keep all that info for the doctor. I would suggest vaccuming 2x a week and using allergy reducing filters for your home.
Do environmental allergies run in your family. If the doctor said she has allergies I would ask what he thinks she is allergic to. I would think there is no reason to be on allergy meds if you haven't had an allergy test done to determine the source.