Ah, this sounds really miserable, I had something similar in my second trimester and the stuck feeling when trying to vomit was genuinely awful, nothing worse than dry-heaving with a throat full of mucus. What actually helped me was drinking warm water consistently throughout the day to thin things out, plus doing steam inhalation over a bowl with a towel over my head, which gave temporary relief but honestly I had to keep repeating it every few hours. Someone in my mum group mentioned saline nasal rinses (like those NeilMed squeeze bottles you can get at Guardian or Watsons), some mums swore by it for flushing out the thick mucus, though a couple found the sensation uncomfortable during pregnancy when everything already feels off. Since yours is getting worse and the general GP already said to just wait it out, I'd really push to see an ENT specialist this time rather than a regular doctor, because they can properly assess whether you need a pregnancy-safe nasal spray or antihistamine instead of just riding it out.