Before writing back to you, I had to consult with a very good friend of mine who is a very experienced optometrist. I trust his opinion a lot and this is what he explained to me:
He said that dilating an eye is not necessary to diagnose a PVD. Just like the other optometrist said, PVDs can be quite obvious without a dilation. He did say, however, that without a dilation, the dr would not be able to rule out RD with 100% certainty. I explained to him your symptoms and he said that with RD there is usually a lot of floaters, a lot of lightening bolts and some kind of vision loss present. Based on the description that you have provided (and which I relayed to him), he said it is highly unlikely that you have RD.
So the optometrist on the site gave you correct information. If you haven't been having an increased amount of floaters, vision changes or more lightening episodes, it is highly unlikely that you have RD. Given that, I think it would be safe to wait until May 17th to see your ophthalmologist for further and more thorough exam.
I disagree with the ophthalmologist who said that you shouldn't have gone to optometrist. Optometrists are highly educated eye doctors and can diagnose a multitude of eye problems. It is basically same as saying "you shouldn't be asking a Physician Assistant (hence, me) questions, you should only ask MD". I know you would disagree with that statement, therefore, I think it was totally appropriate that you saw an optometrist.
Hope this helps you and calms you down. Keep your eye appointment for May 17th just for your piece of mind. Watering of the eyes is not a symptoms of RD. If you won't have other symptoms I talked about earlier, there is not reason to get checked sooner.
Have a great evening. I will not be on line until either very late tonight or sometime tomorrow.