Seedling struggles this year. Please help

[NewCreature]

This is my third year of growing tomatoes from seed and it is by far the most frustrating. Last year, it all seemed so easy. Mindlessly sow the seeds and in about 10 days, all kinds of beautiful seedlings. I don't know what I am doing wrong, but I bet someone here does. Here are some of the details

I have 16 varieties of seeds from J&L, Park, and Baker Creek which I am trying to start in regular size Jiffy pellets. To plant the seeds, I use a slightly moistened eraser side of a pencil to pick up the seed and push it into the pellet. I typically put three seeds in each pellet. I have them on a heat mat in a 70 degree room. This all seems very much in line with what I have read everywhere about starting tomatoes in Jiffy pellets.

On my first effort this year, I only got one seedling to come out of the soil out of 32, and it was pitiful...long puny stem and barely any leaf. I think I had the pellets a bit too wet and I planted the seeds too deep. I am also suspicious of my tap water.

For my second batch, I used bottled water and was very careful not to make the pellets too wet. I also was very careful to plant the seeds no more than 1/4" deep. I am starting to get some plants sprout, but they look pretty pitiful too. One thing I noticed is that I get really heavy condensation on the greenhouse cover. When I check on them daily, I pour the condensation back into the tray. On this latest batch, the pellets seem to be a bit dry, so I have been giving them a little squirt of water to keep them slightly moist.

Any ideas on why I am having so many issues with germination?

As soon as they come out of the soil, I pull them from the tray and put them in another tray that is under an LED grow light 16 hours per day and I am keeping them moist. They are still very skinny and not sprouting leaves very well. I don't believe I have a light or water issue, so I can only assume I need to be fertilizing as I water. Last year I used a fish-based fertilizer and it seemed to work ok. Can someone tell me their tried and true seedling fertilizer recipe?

Mike