Ok, are you still using that electric collar? Have you noticed any behavioural changes - good or bad - since you started using it? From what I understand, they can have a very bad effect on dogs when not used properly.
When dogs are on heat, they do tend to be a bit sooky or moody due to the hormonal changes and can be very aggressive with other dogs until they're receptive. This usually starts as they are coming on heat and when they are going off. Then they go back to normal.
What works best for me when my dog challenges is not to directly challenge back, but to give her a clear command (a positive command, not a negative one) like a heel, to bring her in close, and then do a couple of downs, sits and stays.
In my experience this does a couple of things: it breaks the challenging cycle by giving the dog clear direction on what it should do and getting it to work
with you instead of
against you. It also gives them something else to focus on. If the dog continues to carry on, I will actively use the collar and lead by giving a firm tug each time I heel, sit or down her to redirect her focus to the job. By this stage she is usually quite keen to please, because she is working and looking for positive feedback.
Once she is focused on me and the training, owner and dog become much happier with the situation. I believe the dog really does not want to be in conflict with you. It's usually a sign of frustration that she wants to do something and is not allowed, or that she's not quite sure of herself or what she is expected to do, so gets defensive.
When I see my dog starting to get frustrated, I usually direct her towards a chew toy or something to direct her frustration at before it gets to the stage of challenging. Usually this works well, and after she's had a bite or two or "killed" her rubber toy "prey", she calms down and is happy again.
There are times when you need to be firm with the dog, but not over the top, otherwise it will escalate and if you keep trying to dominate, the dog will become unsure of itself and its relationship with you and things may get worse or you may start to break the dog's spirit. Likewise, you cannot submit, because the dog learns it can dominate you and get its own way all the time. They're not so different to children
Being a master is not so much about being dominant as being firm, clear-headed and giving the dog a chance to work with you instead of against you. In a pack, dogs all work together for the mutual benefit of the pack. The "dominant" dog in the pack doesn't reach that position purely by bullying the other dogs: it gets there through firm, clear leadership and teamwork. Respect is earned and given. But dogs, being pack animals, will still want to challenge in order to move up the rank - just like people. If a dog is confident and secure in its position, and has everything it needs, it has no need to challenge.
These are just my thoughts on the matter. Right or wrong,I've always found it easier to work with animals rather than against them.
Also, your dog is still quite young, and will mature as it gets older. The best thing you can do is try to give her as much exercise as you can each day to release some of that pent-up energy. This will help to calm your dog down. Try to socialise her also, by taking her to new places and introducing her to new things to build her confidence and get her used to the world around her. If you are doing all these things already, then be patient, take a deep breath, and grab a toy and get her to play with you until she calms down. These are the things I would try first.
Finally, do take her to the vet and make sure she is OK. If I have been reading your posts correctly, you say she sleeps a lot and sometimes seems to lack energy - this could be a sign of a health issue. I had a dog that I thought was very lazy that seemed to run out of breath easily and was sometimes cranky and did not like to be disturbed. It turned out she had a kidney disease which was not apparent because she still looked healthy, had a shining coat and ate all her food. However, she did drink a lot of water and used to pee a lot - sometimes in the house. It wasn't her fault: it was the disease.
Don't rule out health issues. Good luck!