I used splenda for the sweetener. I used this machine: https://www.amazon.com/gp/product/B006UKLUFS/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1 I did not pre-chill it, but it got cold pretty fast. After churning it definitely increased in volume, but I don't think anywhere near double I think I'd mostly describe it as soft serve consistency, maybe with a bit near the outside almost completely frozen.

I'm actually working on a blog about this so here goes.

What separates ice cream from a block of frozen milk and cream is the lack of ice crystals (I'm over simplifying, there's also air and other factors).

So when making ice cream you want to cool the mixture in such a way to minimize ice crystals.

The most common way to do this at home is by using a device like this one (https://www.amazon.com/Cuisinart-ICE-21-Quart-Frozen-Yogurt-Ice/dp/B003KYSLMW/s) which has a bowl you freeze 24 hours before hand in the freezer and then pour your ice cream mixture. As it rotates, it freezes and agitates the mixture (to inject air and minimize ice crystals). You get a soft serve like ice cream in about 30 mins and then put it in the freezer to harden.

More expensive machines have a built-in compressor that cools the bowl actively so you don't need to freeze it before hand but cost a couple hundred dollars (https://www.amazon.com/Cuisinart-ICE-100-Compressor-Cream-Gelato/dp/B006UKLUFS).

BTW I'm not endorsing any of the machines in this reply just linking to these devices as examples.

There are some other ways to do this without any fancy equipment. You can put the mixture in the freezer and then just stir it yourself every 15-30 mins until it hardens. Or there's the "bag in bag" method, where you just use two ziploc bags (the outer one filled with ice and the inner one with your ice mixture).

Finally there's a whole different approach that gets rid of the ice crystal by pulverizing them. The most common way to do this is to use a blender. Combine some ice and your mixture into a powerful blender to create ice cream (it will be like soft serve or a really stiff smoothie). Another way to do this is using the Ninja Creami or Pacojet, which takes frozen block of milk and cream and pulverizes the heck of it (and injects air) to create ice cream.

All of the above methods should be google-able. Not sure how much you want to spend but if you're just getting into ice cream in general the best place to start would be conventional cuisinart rotating freezer bowl I mentioned at the start. It's cheap and common and easy to find recipes. My personal favorite these days though is the Creami because it seems to be very forgiving if you're making lower calorie or ice creams with non-standard ingredients.