I have 2 44 watt cfl's and 1 32cfl full spectrum. same ligth that grew the shit out of a royal dwarf plant.
I am not experienced grower but I will try to help you my way. So be carefull with my advices, I will just tell you what I see.
Not long ago we were observing similar problems on this forum, quite good start in the very first days and then cut. It soon came out that the grower had used fertilising additive as a primary medium and put 100% of it instead of 10-20% as it should be mixed.
In the first days little baby relies on food stored in the seed. It does not produce sugars with help of fotosynthesis, it uses stored ones to create a little bit stem, a little bit roots and a little bit leafes. After building basic elements needed to start to accept energy that comes from photons it starts to explore soil with roots. Now problems start if the plant can not accept the environment you offer. Remember that you are Mother Nature in this case.
3 months ago I overwatered my soil severely (first watering lasted for 3 weeks, that tells all). Seeds were put in this too wet and too heavy soil (I was sure it was just perfect :no

. The progress in the first 5 days was quite ok, I think because the roots havent been formated yet and babies have not tested the quality of soil yet. Then they started to expand their roots but they could not.And the growth discontinued.
The same in your case. Babies grew slowly because for some reason, there was too hostile down there in the earth. Then slowly they mature and adapt a little bit, grow a little bit but they are more and more behind schedule. That was in my case and yours also, I think.
Lights are OK, you must have screwed with your soil. You talk about overfertilising, I think it was far too early to feed at all. Maybe some root stimulators but not growth fertilisers. And besides you overdosed. For us, unexperienced growers, heavy feeding is very dangerous.
How I have solved my case? I bought Plagron LightMix andGrowMix which are very, very light and fertilised for only 7 or 21 days. In this kind of soil fertiliser game is quite easy to play because you know exacty how much food it already contains. Nothing or very litlle. That helps with flushing at the end too. You control it 100%.
I think you will sooner or later agree that your plant should be cut and you should start a new grow where something should be changed. And that something is soil I think.