Am I at the end of the road?

Am I at the end of the road? Hello brothers, sisters, everyone. I’ve been using 15 mg of diazepam for 6 years this is my average dose. I quit it completely twice but later started again with small doses because I didn’t know it was such a powerful drug. I’ve never overdosed. Recently it was prescribed up to 20 mg and I tapered back down slowly to 7.5 mg. But today I had such a relentless panic attack that I had to take 15 mg of diazepam. Will I never be able to quit this cursed thing? During my last attempt to quit, I used pregabalin to help and it really did help, but at 7.5 mg I hit a wall. What should I do from here? I’m very anxious; my wedding is on November 2. Today I had a panic attack that lasted 7–8 hours, I thought it would never end. My blood pressure was 160/100. I’m looking for advice from those with more experience.