I'm not a big fan of the prefabbed mass shake products out there. Most of the carbs are usually maltodex, which is very inexpensive... Buying it on it's own is way cheaper than buying a mass gaining shake. I will use NOW's Carbo Gain, which is a maltodex powder. I will combine it with other carbs, such as oats, as well as fats and whey to make my own shakes, when needed. For my vitamins, I use a high quality multi, plus C (and currently D3), so I don't need to rely on a shake to get them. I burn through a lot of cals through the day and just food alone isn't enough to get me to grow, so these shakes do come in handy.
You can use a shake like this while taking insulin. You just need to figure out how many carbs to use with your insulin dose. I wouldn't wait 45 minutes though. With humilin R, I would take my shot, right after I drink the shake. It will take about 30 min to work. With Humilin R, I take 10g carbs for every 1iu insulin, every 2 hours. For log, every 1 hour. Most people think that you should keep fats low while using insulin. I don't know how much they impact, to be honest. I eat a good deal of dietary fat in my normal diet and I don't seem to notice additional fat gain while using insulin. If you are looking for more fats in your diet, try macadamia oil. It's health benefits are similar to olive oil, but it has a high smoke point so you can cook with it, and it tastes great, IMO. I love to use it, along with celtic sea salt on my chicken. Be sure to purchase your oils in glass bottles. Not Plastic.
As for your overall diet plan, its hard to say without seeing you and knowing your portion sizes. I can say that you mentioned eating 3 eggs. Thats not much bro. My girl eats 6 eggs and she is 120 lbs. Dieting or in off season, I keep the protein high. I'd get 1-2g of protein per lb of body weight. Then add carbs, and to a lesser degree fats, to make your muscle gains. If you aren't dieting, you might want to use beef for one of your meals. Fish is good, but a lean white fish like talapia is going to be one of the lowest calorie sources of protein. I save most of my fish eating for when I want to diet down. If you are making gains though, you are doing something right.