I've been in your shoes. I'm a bridge guy as well, and the first two attempts at lateral I got three Acceptables in the afternoon and bombed the morning. I felt especially dejected after finding the morning on vertical pretty easy after 3-4 months of prep and passed on my first go. I ended up taking EET (now AEI) and after that felt the morning went super well. First pass I answered about 35 questions really confidently. For me it wasn't enough to just be familiar with the building seismic/wind, I needed to know it inside and out like it was my job. In addition to EET's courses and practice problems I read through pretty much every major reference I could get my hands on. I read through Alan Williams book, every book on seismic from PPI, the SEA seismic masonry guide, etc. I also read through and tabbed the heck out of ASCE 7 Seismic and Wind chapters. In the end I finished the morning in like 2.5hrs and walked out early super confident. The lateral binder provided by EET ended up being my primary/only reference on like 30 questions.
My only advice is to keep your head up and remember why you're doing it. On my second failed attempt I was mainly focused on just passing and getting a couple of letters on my business card. I spent too much time doing practice problems (like a teacher teaching to the test) and not enough time living in the codes and really understanding the why and how of seismic/wind in buildings. What really helped me was a change in mindset from just passing to becoming a proficient building engineer in seismic wind (not like I'll ever do any building design). Funny enough nothing on the test is really useful for me in my career, I only do displacement-based seismic these days. I also felt the diagnostics are super unhelpful. Who knows if the sections you did well on you just guessed, and the sections you missed you understood the question really well but just forgot one thing.
Even if nothing I said was at all helpful, I'll commiserate and say that the morning lateral for bridge engineers sucks. With more states adding SE requirements for designing bridges it's feeling more and more unfair.