I've run 2:44-flat twice now. One was on a perfect day and one was the cycle after that at Boston last spring so I think I improved a little more even though I ran the same time. I think my fitness and workouts are probably more akin to the 2:38-42 range but my indicator for sub-2:45 was how easy/difficult a 10 miler in 60 minutes feels. If that feels doable, in a high mileage week, in the middle or end of a long run, then you should be ready to click off 6:15s for 26.2. The workouts look great but appear to fall into the 2:46-50 range. I would want to see workouts where you're able to go 8 x 1 mile at 5:50, 4 x 2 miles around 5:45 pace, 3 x 3 miles @ 5:50-6:05, etc., all on short rest. What you're doing looks good and is working. You can definitely get to sub-2:45 in the future.
Go out and run hard at Houston. Since you had a big positive split I would set some conservative-ish goals. Open the front half at 1:23-24-25, try to negative split. It should be more manageable and you're bound to walk away with a PR regardless. Don't feel pressured for 2:45. Go out and enjoy the race. If you don't OTQ, maybe dedicate to a full spring/summer slate of shorter distance races and then target an October race like Chicago with CIM as a backup. I would guess that the paces I put above are closer to your 5k/10k paces versus half marathon for me (5:50). What's your 5k/10k? I would say 17:00-15ish/35:30-36:00ish is probably the ballpark you need or want to be in to realistically go sub-2:45. If your 5k/10k is already there then it looks like a strength problem. I would still work on shorter stuff but then look to add more miles, more long runs, more long tempos, to your next build. Good luck! Go out and crush Houston!