Waterfall chart for stock evolution

Hello all,

I've been watching videos and blog posts on the waterfall chart but haven't manage to set it up in the right way to achieve my needs.

I'm building a stock evolution dashboard.

For each stock piece, I have a date when they entered a specific location (16 different location), and the date when they got out (if applicable).

What I need is to follow up the evolution of the total stock, being able to select a starting date (the first column of my chart would then give me the total stock on that day) and an end date (the last column of the chart would be the total stock at end date), and visualize on a chart the (daily, weekly, monthly) "IN" and "OUT" flows.

I've attached a sample data (weTransfer) : https://we.tl/t-rJU6xgqtDC 

So far, I've achieved to see the daily flow, but this is not visually interesting and doesn't give me the total current stock:

And when I put it in a waterfall chart, it's even worse (and incorrect), it's not counting properly the daily stock and it's not setting the "out" as decreases and "in" as increases:

Any idea on how to present this and the measures I need to create ?

Thank you already!