I have run into several Mini's over the years that always used oil until they got to the low mark then stopped. If it does not go below that mark just let it run there.
I have also had Mini's that had the incorrect dipstick installed and gave an incorrect reading.

Thank you! I hope this is the only leak, but I also suspect some leakage around the timing chain cover. 

..... And glue the gasket to the cover using contact adhesive.... this ensures it will stay in place while you bolt it up.  Leave the engine side clean ..or a very small smear of liquid gasket sealant.

Thin slice of 1/4" fuel hose makes a good seal for the centre bolt....make sure you use the correct cupped (i.e. not flat) washer under the bolt head.

Cheers, Ian

I can't access the photo at work, but if it is a tappet chest cover that is leaking it's an easy fix:

https://www.minimania.com/part/12A1176/Oil-Seal-Tappet-Cover-Sprite-Mg-Midget-Mini-Morris-Minor-early is the seal that goes under the cup washer & bolt.

The chest cover will either have a cork or a rubber gasket - be aware that they are not interchangeable, and upgrading to rubber if you have a cork one fitted may well make things worse.  Stick with whatever style you remove, and though they are sold individually, it's worth buying a pair for a rainy (oily?) day.

https://www.minimania.com/part/12A1139CRK/Gasket--Engine-Tappet-Lifter-Cover-Cork-Sprite--Mg-Midget--Mini--Morris

https://www.minimania.com/part/12A1175/Lifters-Tappet-Cover-Gasket-Red-Sprite-Mg-Midget-Mini-Morris

 

That appears to be a valve tappet cover. (In behind it are the tappets that ride on the valve cam lobes.) Gaskets are sold in pairs because you have two covers side by side.

I cleaned the engine, and this is the only place that looks like it could be leaking from.... I'm just not sure what this is called. It's right behind the motor close to the headers. 

https://drive.google.com/open?id=1VUftFid5kFuXmNVioQTy8946SAx2FOx5

Unless your engine is extremely dirty, you should be able to get an idea where it is leaking by looking at the pattern of oil/dirt on it. I'd have a close look from the bottom up, front, back and ends to see if/where the oily area begins. In any case, here's the usual suspects:
- oil filter - depending on type may be loose, improperly installed, broken seal etc.
- rocker cover gasket (don't overtighten or you distort the gasket)
- rocker cover bolt seals
- tappet cover gaskets on the rear side of the engine below the exhaust manifold. Note: depending on your engine you may not have these.
- crankcase breathers. Depending on your engine you may have one to possibly 2 -4 3 in various locations. Early 850's had a hose from the top of the rocker cover to the air cleaner housing. A+ 1275's have one on each end of the engine. Oil may be coming out of them due to internal crankcase pressure.
- crankshaft front seal (oil around the pulley/belt area)
- crankshaft rear seal - oil dripping from the hole at the bottom of the clutch housing.
- engine to transmission gaskets/seals
- driveshaft output seals each side of differential housing

One other scenario is that it is burning oil rather than leaking. This would be most likely valve seals or piston rings.

clean the engine with a degreaser when it's cold.  run the engine with paper or cardboard under the engine, and then carefully look for the leak(s).  Oil like water will flow down due to gravity. It may leak higher up but it will run down the side of the engine/ gearbox. 

So. I've noticed that my oil level will not stay at Full. I have been checking it every day, and it also never goes below the Low mark either. Would it be a good guess to say that the leak is coming from the rocker cover?