Your history fits reflux-related throat irritation with an allergic post-nasal drip much more than any lung disease - normal HRCT with no fever or weight loss is reassuring. Morning sticky sputum, throat clearing after tea, and flares in humid weather or near trees all point the same way. The choking feeling is an irritated larynx, not your chest closing down. This settles well once reflux and the allergy part are treated together.
Next Steps
Start a 6-8 week trial of an anti-reflux medicine before breakfast plus a non-sedating antihistamine at night, keep dinner light and 3 hours before sleep, and do saline nasal wash daily. If choking episodes or morning sputum persist beyond that, we should relook with a fresh chest exam and spirometry. Consult me on Practo with your HRCT report and I will set the exact regimen for you.