Tomato seedlings in the house versus in the unheated greenhouse

First I need to confess a good deal of these results more than likely have a lot to do with the lack of care. I was excited to buy seeds, but I just haven't been into the process. Normally it's on of my favorite parts, but this year I'm doing it because I bought the seeds, and I want the veggie, but it's more a chore.
Normally I check them every day, do they need water? Should I adjust the light? This year I turn the light on and off every day, but it's more like when did I water? Oops the light is touching the plants.
Today I noticed the tomatoes inside aren't looking very good. The leaves are turning yellow. They are planted in 50% organic compost, and 50% organic soil. Odds are it's not a nutrient deficiency, so it's water, to much or to little. Or light to much, or not enough. I don't think it's to much water, I just haven't been watering very much. It could be not enough, but though the pots aren't heavy, the soil doesn't feel particularly dry. The lights are not very expensive, they are grow lights, and worked well last year. Also it's an old drafty house, and not that warm.
My process is I start seeds with a heat mat and a humidity dome in 3/4"soil blocks. Once the plants sprout 3 to 5 get planted in a 2" pot. Once they have 2 sets of true leaves they go into their own pot (this year it's a cup, or 3" pot I'm still searching for what works best) now 1 of each will stay in the house, and the rest go in the greenhouse. The funny thing is I consider the house insurance because the greenhouse doesn't have heat or a fan, so it can get cold at night and quite warm during the day. Last year this worked well. Inside and outside grew well until mid spring when it was just to hot in the greenhouse.
This year even with the constant weather change (last week it was high 70 making it high 90, it was 102 on afternoon. This week the temp has plummeted. In the 50s during the day it was 65 in the greenhouse. Mid 40 at night. ) the tomatoes in the greenhouse look so much better. I have been adding a tiny bit of organic fish emulsion, and a tiny bit of big bloom an organic fertilizer. Every other water. It smells too bad to use in the house. All the pictures are the same tomato, planted at the same time, some soil, same pot.
I really need to pot up the peppers, so I don't have pictures of them yet, but though the few that are in the greenhouse look healthy the same ones in the house do seem larger, they seem to be growing faster.

Last year mine turned yellow. I was told that my compost was still too green. Another family member planted into a straw bale and had success.