How to pack light for six month trip

Managed to pay for my ticket today - what a relief!
Bought carry-on size, roller and handle luggage.  On sale, but still had to pay $101.00!  Yikes. 
I am planning to travel light - sort of.  Each suitcase weighs just under nine pounds - and each bag needs to be below 50lb.  This will be interesting. 
Packing light for six months - that means at least two seasons, more likely it will enter a third.  I have decided to focus on the seasone presenting now because it will be winter soon enough.  This means bulky, albeit comfy, sweaters, long pant, leggings or tights, favourite mittens and scarf, toque, a warm coat, a light coat (I am thinking positive thoughts) boots and walking shoes.  This in addition to the books I already pared down, puppets, more books and then any toiletries I will need.  And medicine.  Yup, I do take some medications, better to take with me until I have established what is where and available.  Heck, I even have a requisition to take with me to show a doctor what blood test I need.  I also want to take my bike helmet - I wonder if that would be considered a personal item like a coat is.
Moving out day Weds or Thu!  My stuff should be fairly easy, mainly just teaching material I do not use on a regular basis.  How on earth I managed to accumulate 20 plus file boxes of stuff I do not know!  When I think about it teaching is done everyday, so it makes sense.
I am going to pack my turquoise huggable puppet in my carry-on bag - should provide some interesting looks if nothing else.  Her name is Sylvia.  I think Sylvia will open up doors for me that a camera might not.  With children anyway.
Getting excited!