I have been diagnosed with GERD and LPR by an Ear Nose and Throat doctor after many tests. Like you I have suffered from the lump in my throat, sore throat, sinus issues, and lung issues. I don't have much heartburn though, but my throat really burns sometimes. It comes and goes. I also have lots of mucus and it is beyond annoying at times. Some people have had success with surgery but I'll let those folks tell you about it. I have tried to stay away from surgery. I tried 4 different types of proton pump inhibitors. I wasn't able to tolerate any of them. I had lots of side effects. I have tried diet and other lifestyle changes and have had some success with them. One book I recommend is Dropping Acid by Jamie Koufman. She specializes in voice issues and LPR. Her book is very helpful in understanding what LPR is. She discusses lifestyle changes and includes a diet plan for people with LPR. It's a very good place to start. I went on her diet and it helped. It didn't end my suffering, but it helped. I've also read a good book called Fast Tract Digestion (Heartburn) by Norm Robilliard. His approach is different from Dr. Koufman's. He also includes a diet in his book and I've been on that one too. Again, it helped me. Dr. Koufman and Norm Robilliard both have very good websites with a lot of information. Dr. Koufman's website is www.KoufmanReflux.com. Norm Robillard is the founder of the Digestive Health Institute, website is www.digestivehealthinstitute.org. Norm is not a medical doctor. He is a microbiologist and researcher. He had GERD for a long time, changed his diet and no longer has GERD. He thoroughly explains it all in his book.
I think both of those books would be a good start for you. I'm currently on something called the Whole30 diet. It's a Paleo diet. Pretty strict. You stay on it for 30 days. I'm on Day 13. I will say that my throat was hurting terribly just before I started this diet and it does not hurt now. I'm hopeful, but I've learned to be hopefully cautious. The book that explains the diet I'm on now is It Starts With Food by Dallas & Melissa Hartwig. It's not specifically for GERD/LPR. I think it would help to read the other books first.
This forum has helped me so much in understanding my condition. Some people seem to have success taking the proton pump inhibitors (PPIs), others not so much. Some go straight to surgery, others try to stick with diet change and lifestyle changes. Some are trying to get off of proton pump inhibitors. It's a mix and not everything works for everybody. It helps to get as much information as you can and then you can decide what is best for you given your circumstance.
I can say pretty assuredly that stress does make this condition worse. And I've gone back over the last 3 years over and over again to try and figure out what caused my GERD/LPR. It is crazy making for me so I try not to do that anymore. I have it, it seems to want to stay for a while and I am pretty determined to do whatever I can to get rid of it. Unfortunately, I haven't learned much from my own doctors. Some of them don't know much about LPR, others don't have the time or inclination to educate their patients. That's why I recommend the books. You might have a great doctor who can help you make your decision and if you do, hang on to them! I just didn't so this is what I'm doing. I hope some other people stop by and give their story and what has worked for them. There are lots of good threads on this forum. You can use the search feature at the top of the page to find what you are interested in.
I wish you the very best.