Sticky dough doesn't hold shape. Please help!

Hi guys! I've been baking sourdough for 2 months now and although the finished loaves have satisfiable rise and crumb for a beginner, I have 2 main issues that seem to follow me no matter what recipe I choose; 1. I mostly follow recipes that include video tutorials or at least pictures so I can compare how the dough looks at each stage. My dough is always more sticky than the dough from the video/picture and it never gets completely non-sticky. I've been religiously flouring the proofing basket since I am always afraid the dough will stick (fortunately it doesn't, but I assume it's only because of the excessive amount of flour I use). 2. My dough never holds shape in any stage. Not when I do S&Fs (I've tried doing from 4 to more than 20 of S&Fs, the result was the same), not when I preshape the loaf - I get really nice surface tention though, but the dough looses shape after couple of minutes, nor when I take it out of the basket. Some more info: - my starter never doubled when I kept it at 100% hydration (feeding it once or twice a day at 1:1:1, keeping it at 23-27 °C). The first time I fed it at 90% hydration it doubled, almost tripled when it peaked - I tried different recipes from 60-80% hydration - I tried different proofing times and temperatures at differently stages - I tried reshaping the loaf after taking it out of the basket, just before putting it in the oven - it didn't make a noticable difference, it still lost shape in the oven before springing (I use pyerx since I don't have a dutch oven) I'm making another loaf on Tuesday and would really appreciate any tips! Thanks and have a lovely weekend :)