When you look at efficiency it should always be Gravity and Volume at each step. This may be why your overall efficiency is not what your estimate in BeerSmith is set to be. You may aim for 2 gallon in the fermenter, but how much actually made it into the vessel? While this may seem onerous at times, taking and recording your gravity and volumes throughout your process will make your efforts more predictable in the long run.
Your batch size should not matter much in terms of your efficiency numbers as I brew 3 liter, 10 liter, and 14 liter BIAB and my efficiency (mash and total) between all three systems is pretty consistent.
In terms of where your efficiency numbers should be, this is more dictated by your process and volume losses in your system. The ideal number is the one that you can repeatedly hit every time. Once you achieve consistency, that is the time to really look at what you can do to improve your efficiency.
So looking at your numbers, you are getting a little better mash efficiency than estimated by BeerSmith. Your lower Brew House Efficiency (BHE) combined with the higher than target OG indicates that you had less volume reaching your fermenter than your target. Where your volume losses occurred should be the first thing you try to track down. Measuring your actual boil off rate, losses to trub, and other areas where wort is left behind and feeding that information back into your equipment profile will improve your estimations in BeerSmith.
While that is being worked on, entering the efficiency numbers back into the profile will help you 'dial in' the sugar extraction from your mash.
As you go through this process, feel free to upload your completed recipe as a .bsmx file and ask questions. There are quite a few people on the forum who are glad to help you make it better.