Super!! Done before or not, Andromeda is a fascinating object visually, and interesting that it is our nearest neighboring galaxy and is on a collision course with our Milky Way galaxy. It’s also a great object to practice on. I think it is simply overwhelming that our cameras can see things like this that appear just as a smudge to our vision. I wish things like this would let more people realize their significance in the cosmos.
You’re well on the way with photographing the subs (individual frames) and the next level of magic is in the processing, for noise reduction and pulling out fine detail. An additional bit of image quality can brought out by using darks, flats and bias frames, largely for further NR. @Dan_Kearl has a system going that is working well. Being compelled to do everything the hard way, I went with PixInsight, which is the top level software (a complete processing package for serious astrophotography) but comes with a learning curve. There is a lot of information online about it.
I posted an M31 image a while back. It isn’t the best I could have done, but you can at least see the noise is better: