Since you are clicker training the heel make looking at you part of the behavior. Walk around your yard and only click/treat when she is heeling and looks up at you. Then do it on a small walk. But do you require her to heel for the whole walk? I've never been a fan of that, it takes sooo much of the metal stimulation out of the walk. i understand maybe using the walk to teach her to heel with distractions (see another dog or person coming, put her in a hell so she does not go to meet them or chase them) but for the whole walk I don't see the point. Now that does not mean I think she should be allowed to pull, no not at all, you can still train her not to pull on a walk without making her be in a perfect heel. I actually made great progress with my neighbors dog in one walk. I went out, treat bag full with clicker on wrist and clicked every time she fell or remained near my side. By the end of the walk she would catch herself near the end of the leash, look back at me with a BIG grin and slow way down so she could get her click. She always made sure I saw her to, she'd stare right up at my face for her click and treat. Give me maybe three days and I'd have had not a single pull from her I bet.
Also remember all dogs are different, you cannot hold one dog to some standards of what she "should" be able to do. simply be thankful for any progress no matter how small or how long it took.
Another thing I would like to learn would be to get my dog to sit at my side while at rest.
As for sitting near your side, use clicker training again. Sit in a chair with your dog on a leash, don't hold her back unless she is at the end of the leash. if she sits click and treat. if she sits and stays click and treat every few seconds (slowly increase the length of time between clicks). If she lays down, click and treat (then follow the same procedure as the sit). You need to let her make the decision but make her WANT to do what you want her to do, that's what clicker training is all about. Keep sessions short at first, when you are done give one more click and treat then stand up. Only end the session when she is doing what you wanted (while she is sitting or laying) and when you stand entice her to leave her position (let's go buddy!! as you crouch down).
Next time make the session longer. Soon the dog will realize to quickly get a treat she should sit or down as soon as you sit and the longer she stays the more treats she gets (by slowly increasing times between treats she will also learn endurance..."if i wait I know I'll get a treat, even if I have to wait a long time, it will come") and then you can simply give one click and treat near the end (but always make her wait until you stand up to leave).
If you meant something else (like sitting at a curb when you wait to cross) tell me, I might have misread.
I also wanted to add, good for you!! it's great to see a pup know so many things, you must be working hard, and I'm so glad to see you do clicker training, did your breeder do that as well? I'd love to see pics of your pup in general dog chat