Congrats on the new addiction! I started at 30 and hope to do it forever.
You'll get some good advice from guys here that have boarded for a really long time, but from a second year rider with 50+ days on the mountain I can share some experiences that helped me along the way.
First, stay out of the blues if you can't even do linked turns consistently. Many here will say speed helps, but only after you've got the fundamentals down. Greens will give you plenty enough speed to practice whatever you need to do. Going down terrain too steep for your ability level can actually hinder your progression. I've seen it too many times with friends I ride with.
Second. Really focus on your front foot. Do whatever you have to get that front foot engaged. I used to actually unstrap my rear binding and go down some really mellow terrain with just my front foot. Learning to engage the sidecut of the board, especially by initiating with the front foot, will work wonders for board control.
Third. Work on your balance. A lot of problems with beginner turning could be balance issues. This means keep your weight centered on the board. Oftentimes because a beginner isn't comfortable on the board, instructors will tell them to keep their weight forward. The beginner will actually think they are forward on the board, but in reality, they are more centered. Riding in the backseat will cause a lot of the problems you mentioned.
Finally, have fun! You'll have plenty of years left to learn. You have a three year head start on me.