Comprehensive list of supplements worth taking for muscle/strength/power & body composition. Everything else probably isn’t worth your money or even your time in taking it.
Intra-workout carbs (during training) ( sugar Gatorade)Whey Protein (during or around training)Creatine (during or around training)Casein Protein (before bed)Caffeine (before training)
Advanced **Endurance **Supplementation
FYI… This is not a formal recommendation to anyone.
It was compiled for my wife.
It is the full list of anything worth spending money on as an endurance athlete, in my opinion. Bicarb left off because of complexity of supplementation. Cost was not taken into account when compiling the list.
The question I was asking when I performed the comprehensive lit review of virtually all available supplements was “will this make Michelle faster at either triathlon or cycling, in any reliable or ‘probably reliable’ way?” If the answer was “Yes” or at least “quite possibly” it made the list.
I purchased it all through bulksupplements.com via amazon. I would say there is either a very strong placebo effect of the combined power of all that stuff or it works pretty well, in my personal experience. Michelle wholeheartedly agrees and takes them religiously because of her perception of its effectiveness for performance enhancement.
Casein options:
Optimum NutritionDymatizeAscentWhey options:
Optimum NutritionDymatizeAscentCreatine:
Creatine from Bulk Supplements on Amazon (cheapest, best, easiest, all in one)
Endurance supps:
Beta Alanine, 1kg, Bulk Supplements via Amazon
Beet Root Powder 1kg, Bulk Supplements via Amazon
Citrulline Malate, Bulk Supplements via Amazon
Caffeine from Bulk Supps on Amazon is great. The cheaper the better. This one is cheaper as of last checking.
Creatine from Bulk Supplements on Amazon
Sodium Citrate
No affiliation to any of the above. I just have all the above stored in TextExpander 
With regard to your specific supps you currently take:
Vit D, fine. Maybe healthy. Great if you live in low light exposure area.Omega 3 gels, probably waste of money.Greens mixes can work great for veggie substitution especially in a time-crunch or for some daily efficiency. One tradeoff is that they tend to be much less filling than actual veggies, but if you’re not dealing with much hunger, then you’re probably good to go! If hunger increases, definitely increase veggie volume!Collagen probably doesn’t have an ideal amino acid profile to support body composition as well as whey protein or even soy protein. Definitely not ideal for meal replacement or use during a workout. As far as it’s benefits for other purposes (hair, nails… etc.), my jury is still out. If you’re going to use it, just count it toward your protein macros for the nearest meal, and maybe only do half your protein from any given meal as collagen. I don’t spend money on it.
Re: your other proposed supps:
Zinc: waste of moneyMagnesium: waste of money unless you need a laxative, in which case you should use Magnesium Citrate (no affiliation).Calcium, K2, B12… shoot just take a multi. Honestly, if you’re getting a fair bit of variety (lots of veggies), you probably don’t need a multi-vitamin. If your diet is occasionally like mine…somewhat one-dimensional and highly repetitive… then yes, a multi-vitamin is an acceptable, but still probably useless way to cover your bases. I’d go with the cheapest option. Walmart or Amazon brands or other generic low-dollar options are just fine. If you need anything specifically out of your multi-vitamin, then you should probably be taking that independently, rather than paying double or quadruple for a multi-vit that contains whatever special interest/need you might have. Spending more on multi-vits, and other supps, ironically, just as frequently makes them less useful than more useful, because some supp company got a wild hair to do things a little differently. Get the cheap stuff.
Hope that’s helpful!