I' m an Idiot.... 650 daytona

Hi all
I've just bought a great bike But I think I have been a complete idiot.. I locally bought a 2005 Daytona 650 with 12k on the clock. I was sold to me with a problem, an electrical issue, it wouldn't charge and when the fan kicked in the clocks would die. I didn't think it would be to bad to sort out as although I'm not an auto electrician or mechanic I'm actually a domestic electrician and plumber so quite handy. The previous owner took it to a Garage and they replaced the regulator/rectifier and bypassed the alarm as he thought that was the cause but it was not.
After a bit of research I replaced the Stator, it was completely shot... And now its charging fine with 14+ volts while running.
All good so I thought, but while I changed the Stator some oil came out of the crankcase as expected.
The problem is I replaced about a litre of oil as that is what I thought needed to be replaced, it was a bit low on the dipstick but I thought a quick test ride wouldn't do any harm as I was going for a full oil change next week and didn't want to spend £40 for 4 ltrs at Halfords. (why cant they sell it in 2ltrs?? it's either 1 or 4.) Any way I went out for about 5 miles everything fine, then a mile from home I noticed it wasn't quite running right, a bit difficult to explain, a bit rattly and not as meaty??
Just after I noticed that, the engine management light came on, I rode it slowly home for abut a mile then switched it off, when I switched the ignition back on, but did not start it and now it says low oil..
The question is have I killed my engine does anyone know the best or worse case scenario I can expect or what to do next to avoid any damage.
Many thanks
Matt

 

Cheers for the reply, enjoy..

 

It was just showing on the dipstick like about 2 mill

 

All is ok, doesn't seem to be any damage bar a couple of remaining issues.
Changed oil and everything running well, However when I give it the beans down the dual carriageway the engine light comes on, if I stop turn off the ignition and back on again it clears, any idea what this could be?
Also following my low oil episode the low oil message keeps reading when I turn the key but goes off once it's fired up, how can I clear this?
Thanks

 

well it says low oil in text. I don't know if it means level or pressure, I'm assuming level as it was low...
And I have never seen it before.