Sounds normal to me.
An empty mag allows the mag follower to ride up and push the slide stop up and lock the slide back.
If you pull the slide back with no mag in the pistol at all....yes....the slide will not stay back and it will "go home."
If you want the slide to stay open, when you pull it back on a 1911 with no mag, you can use your thumb to push the slide stop up at the time you bring the slide back with your left hand. I do this quite often.
You would benefit greatly from going to the various 1911 web boards and reading up on the "manual of arms" on the 1911 pistol. It varies from other autos, but is easy to master, once you have messed with it for a while. Buying a copy of the old US Army Field Manual on the M1911 is also never a bad idea. they can be found online at many Army surplus dealers for 10 bucks or less.
Unlike many modern autos, the M1911 was designed back when soldiers were expected to learn and master their sidearms...not designed to fit the lowest denominator like so many guns of today.
Once you get used to and familiar with the M1911..you will probably love it's simplicity and it will be second nature. I grew up shooting Dad's duty M1911 (Dad was an MP in the Corps) so I forget how many did not grow up with this pistol and know it as I do.
Have fun, be safe and welcome to the addiction! LOL
- brickboy240