sourdough problems

sourdough problems

Hello Good People

I sure need some help … got 2 problems and do not know if they are connected . Started baking again after two years off, and am extremely frustrated 

Until getting into the oven , everything seems fine, good rise, overnight proofing . Oven 475 F. 

The bread rises but it looks like it can not stretch enough ,  the bottom is not flat but oval and the final shape is almost round, inside is too dense. 

In addition , everything is white (also bottom), but a stripe around the periphery , which is very nice golden brown, Steam by vaporizer in the first 8 minutes. 

Never happened to me in the past, same recipe, however, oven is new

It will be great if somebody knows what is going on here.. 

Source: Fresh Loaf