These are looking good! I think the first one is my favorite. Overall the proportions and structure are looking good. Be careful with the pelvis of letting it get too small. It's a good deal bigger than you would think. Right now It seems like its a little small on the figures you have. Try to push more of a cure to the center line to accentuate the action of the pose. I've found that it's helpful to have this first gesture lines be almost over stated because as you add the structure and flesh out the form, the pose tends to tighten up.

I actually think you're doing quite alright with pelvis position, so just keep doing that! Here are a few thoughts about what's confusing when drawing the simplified pelvis. So, what you are supposed to do first is read the bony landmarks and that tells you about the pelvis position. It gets a bit tricky when drawing it simplified as a bucket or a box though because it is not the pelvis exact shapes and people interpretations can vary. Some will use the box and include the great trochanter (a landmark on the femur) in it. Some will make the bucket go below the genitals, as to include the ischial bones, but others will stop at the pubic symphysis since the ischiums are buried in muscles and never visible. Some will make the box or bucket go as high as the pelvis highest points (the iliac crests) while others cut it at the sacrum and iliac spine heights, and will add a bit more heights when adding the iliac crests. Don't panic, you don't need to know all these details right away! Using the simplified pelvis is much more important to develop a feel for its position. What I am trying to explain is that there is not one single approach to simplifying the pelvis and you just... have to feel your way in placing it by doing exactly what you're doing and doing it a lot. You coud also try drawing the pelvis as a box, which clarifies front and side plane more. Sorry about the lengthy answer, haha, pelvis are hard!