Doing pull sets without a pull buoy

Pulling without a buoy is a great drill IMO.  I would definitely think of it as a drill and not something you'd do for set after set.  Just put your feet together and try to keep them still and near the surface of the water.  Some people put a band around their ankles to help keep the feet from kicking 'involuntarily'.  Not easy!

Our swim team does plenty of "band work". This is Pull with a rubber band around your ankles, and no Pull Buoy. Now I wouldn't recommend this for a newbie, but it can pretty much immediately identify imbalances in your stroke (your legs will start swaying from side-to-side, may sink to bottom, and then you pretty much come to a stop). It is an extremely difficult skill to swim with no pull buoy AND a band around your ankle. Without the band, you will naturally kick a small amount.

I have seem people doing pull drill with theyr legs crossed at the ankle - so that they don't kick.  Never tried it myself. 

As kids, we used to do the pull drill with a kickboard between our legs.  Just hold the kickboard between your thighs.  My mom said we looked like a bunch of little sharks with the kickboards as the fins.  Didn't have a specific pull-buoy back then.  As long as you have something to keep your legs still and balance, you'll be ok. 

The pull sets are isolating your arms.  Legs aren't to be used.  If you don't kick and your legs don't sink, then you are an advanced swimmer.

My guess is you won't be able to do it without a pull buoy lifting your legs.  If you don't have a buoy, then you don't have fins.  But if fins are available to borrow at your pool, putting those on can add enough lift to keep the legs high...even when not kicking.  So try that if they are available.

Without seeing your stroke, hard to say, but that's actually a good thing and how it should be done (unless you're actually pointing your head downward or submerging it!).

You can try arching your back really hard.  But you also need to relax the abs and hip flexors or that pulls them down.  I mentioned above that swimming like this is a very advanced technique.  You were right to drive the head and shoulders down.  The next step in the process is to swim fast.  Don't mean to be flippant...if you swim fast it lifts the legs up behind you.

I had to do this last week.  Had a very hard training day capped off with an open water swim in the evening.  My legs cramped like crazy, all the muscles.  The only way to try to avoid the extreme cramping was to NOT use my legs at all.   But when I did that I had to really step up the tempo and almost sprint to keep the legs high.

I know I can get one and relatively cheap from a local sports store I'm just broke this week,lol.

 I do have kickboards, dumbells and noodles available at the pool though and I use the kickboard for my kick and catch up sets so I might try that. My legs sink even when I do kick so that's probably not a very good test of whether it's working or not although yesterday wasn't really a good test of any sort of positioning as I had my head out of the water most of the time due to not having my goggles with me.

Won't work. I live in Australia.