Great.
At the point you are painting, there are MANY more accurate small details you can add that were lacking in the generic image in that book.
~The Richards family, (father, mother, two pre-teenged sons and an infant) were leaning against the bulkhead beside the second class entrance on their boat deck. All but the infant had life jackets.
~Norman and Hilda Stones were at the railing, preparing to slide down some ropes. She was removing their travel money from her bag and putting it into his pockets.
~there were at least 83 people in the vicinity of boat 15, and 35 in the vicinity of 17. 15 pulled an additional twenty people out of the water immediately after the ship sank, and 17 at least ten. So, you'll need a fairly tight crowd aft on the boat deck. There was a father with an infant who did not make it into 17, if you want to get VERY precise.
~Mr and Mrs Naish were in the angle between one of the unlaunched second class lifeboats and the rail, watching the horizon move as the ship heeled over.
~Mrs Logan and a crew member were removing her infant son, who she had placed inside her life jacket.
~Structural damage. Okay...this is neat. Apparently, something big fell off the ship at about the time you are painting. Two witnesses who were on the docking bridge described the bow falling off. Obviously THAT didnt happen, but many MANY people who were in the water to starboard described the sudden, violent, collapse of something forward on the boat deck. What that something WAS cannot be exactly determined, yet, but quite a few described it as a section of the liner's side caving in. Others described it as a pile of "paraphrenalia" falling off the funnel deck and into the water. Who knows?
~Mrs. Bretherton, who was about to enter a boat with her 3 year old son, had noticed smoke coming out of the floor, and the wall vents, when she ran down to her C Deck second class cabin to rescue her child. Others commented on the presence of smoke in the ship. You need at least some smoke seepage in second class... witnesses saw it. It wasn't like the major smoke visible forward in first class, but it was there.
~Marguerite Kay, 9 months pregnant, and her pre-teenage son had just stepped out of a door on to the boat deck.
There are many more authenticating details, but those make a good start.