Hi Melissa,
It's going to take a little while longer, but she's on her way-- especially now that she can self soothe to sleep (hooray!). When you put her down, make sure she's awake, and a little drowsy-- you want her to go through the stages of falling asleep in her bed, since they're the same stages she will go through when she reaches the 45 min. jolt. So, awake but little drowsy into bed.
Make sure her room is dark as can be. Nothing to catch her sight when she partially awakes at the end of a sleep cycle.
I'm wondering if you do a modified wake to sleep approach-- going in at the 30 min. mark, and just rub her head a bit, to disrupt her sleep cycle a wee bit.. nothing too much.. and then place your hands on her limbs to help her resettle?
Another thing.. how does she come out of the sleep cycle.. is it a cry or just wide awake and alert?
Hang in there.. she's going to get through this! It's a learning process.