I can relate to the anxiety attacks - being relatively new to diving and only warm water can't do the 7mm wet suit required up here in the northeast. I take my security blankets with me my camera and my husband once I get down and start snapping I am a happy girl. I started when I was 44 so it is never to late.
I also tell the Dive Master that I am high maintenance and I think it gives them something new to do since they sometimes go the same places a couple of times a day. I have trouble on the ascent and they are so great taking my hand so I don't zoom up. Can't say enough nice things about the DM's in AC. We also have a separate DM for my daughter (10) well worth the money.
Going back to snorkeling is hard when you know what you are missing down below.