^^^ Yep. Kelp is essential. I'd put some alfalfa in there, too. Here's a good rule of thumb for adding "nutrient" amendments to your soil mix. Take equal parts (if using kelp, use twice as much, in other words two parts kelp, one part this, one part that, one part the other thing...)of all your amendments and mix them together thoroughly. Then use 2-3 cups of this mix per cubic foot (7.5 gallons) of base soil (compost/ewc, perlite, promix or peat moss). Your guano is one of these amendments. I mix large amounts of soil when I make my own. You'll have to do the math for small batches. I can't help with the Epsom salts. I don't use it in my mix. But I'm sure that it's ratio is WAAAAAY lower than what I just described, so don't be using one part Epsom salt in your amendment mix! It would be bad.
Am I understanding things correctly? Are you using Pro-mix as part of your soil base? And you added lime to it? Pro-mix already has lime in it to counteract the acidity of the peat moss. If your making a small batch of soil, I'd start over. The excess lime may give you problems down the road.