OP,
I am glad you are OK. That is a biggy right there.
It seems like you have a history of "panic" in the water. Even in your Discover Scuba class you stated you had a feeling of panic. Did you discuss this with your instructor? For an instructor to take a student back in to the water who was panicking as horribly as your were, is not very responsible. It is down right dangerous IMO. I understand you have a dream of SCUBA diving. All of us here share that passion, and do not want to see anyone needlessly hurt pursuing that dream. You could have been seriously hurt. I can understand taking you in the water to snorkel. However, once you showed those symptoms again, you should have been pulled from the water immediately. No arguing. You need to get back in the pool and work in the pool for hours on end until you are 100% comfortable in the water. Then you need to be in shallow, less than 20ft, water gradually working your way in to things to expand your comfort zone. I have no doubt that you can do this and make your October trip, but to think that you are going to be OW ready now, or even after one more session is ludicrous in my mind.
I wish you safe diving, and a lifetime of happiness pursuing your dream.