tartine style country loaf

Hello everyone , 

have been experimenting with tartine style loaves and have been getting very inconsistent results . 

A couple of times my loaves were perfect with this thin splinter like crust and a gelatinous crumb which gave it a custard like mouthfeel. However now i am struggling to get that again .The crust is turning out to be thick and heavy with a crumb that looks ordinary without the sheen it originally had. A few things have changed 

1. The few times the loaves turned out well It was during the winter months with low humidity and now the humidity is slightly higher . 

2. the dough doesnt seem to be as elastic as i remember even though the flour is the same., could it be the humidity has affected the flour? do i need to reduce the hydration from 75% to a lower amount?

3.Is it a problem with my leaven? as i am making it slightly stiffer than before to prevent it becoming soupy too soon . I feed twice a day.

4. My oven has changed as well. previously used to bake directly on the deck and spray the inside with water to generate enough steam. Now i have a deck oven with a steam system but it doesnt produce a cloud of steam at all its just a hint of moisture in the chamber .

appreciate you advice.