troubleshooting 3/16 gravity

It’s my first season using tubing. I’m in Eastern Kansas and I’ve only learned what I know from you folks here and other online resources.
My season here is early and I tapped 1/8/22.

My setup:
Five lines of 3/16 averaging 500’ long with 17 taps on each using 5/16 drop lines with stainless spouts.
I’m using the green CDL fittings.
They all run from the top of a hill (which I’m estimating by the looks of it is a 50-60’ elevation from the collection tank)

I also have 14 sap bags in another stand of maples 1/4 mile away, mostly as a control group because I don’t know what using tubing is supposed to be like.

The weather has been weird and everything is starting late, but just this last weekend through today we got a real sap run. Proportionally, the bags have been outperforming the lines, and I’ve had suspicions that my lines aren’t set up right, but the weather HAS been weird, so I’ve been giving the lines the benefit of the doubt, while continuing to research and look at videos/photos of other people’s gravity setups to double check I did things right.
Here’s why I have questions:
With this sap run we got, I went this evening to collect and the 14 bags combined had 25 gallons, and my collection tank from the lines had 50 gallons.

The tank should have 6x the amount that the the bags total, as there are 6x the number of taps on the lines. So there should have been 150 gallons in my tank instead of just 50. There has to be something not right with my lines.
Here’s a list of facts that might be significant in helping you help me:
1. I do not have “end of line hooks”. I just used my tubing tool to force the end of the 3/16 tube into the 5/16 dropline tube for the very end (or beginning?..the dropline from the highest tap). It looks very airtight...maybe it’s not?
2. I do not have a vacuum gauge. I was curious at some point and pulled a tap out way upstream when the line was full of sap and immediately all the sap flew down the tube and I heard a sucking gurgling noise and putting my finger over the end of the tap felt like a little vacuum hose until there was no sap in the line anymore. After that I learned what the fine, soapy looking airleak bubbles look like. They took forever to move all the way down and out, but once they were out, sap in the line started moving faster again which leads me to my next question...
3. The sap in the line moves slow. Like 3”/sec. Is it supposed to creep along like that? The most I’ve seen come out of the end into the tank is like when you crack a faucet open enough where it goes from a drip to a little stream. There’s bubbles that come too, like big sputtery bubbles though.
4. After the lines get to the bottom of the hill, the slope shallows out in route to the tank. Not flat, but not as steep as the hill is. It still picks up 4 or 5 taps in this shallower area before it gets to the tank.
5. I’m pretty sure the tubing system is to be totally sealed except for the end that runs into the collection tank, but since I’m asking questions I have to get this out of the way: Is it really? Is there such thing as too much vacuum/everything being too tight? Like how a straw you plug the top of doesn’t allow the liquid do fall out of the bottom. Could this be what is happening? So what happens if both ends are open?
6. There is currently no squirrel damage
7. All the taps are above the laterals
8. I tried to run the line in an S rather than a W, but it’s really more like a W.

I’m just disappointed in how little production has come out of the tubing vs the bags and I want to fix it before I lose the next sap run.

Long post, sorry. Thanks for reading. See you in the comments. Happy to clarify anything I did not explain well there.