Ever heard the old joke about the farmer being asked how to get to a nearby famous landmark? There are a hundred versions of it, but there's one commonality...
His reply is always, "Well, you don't want to start from here…"
The thing about GAS* is that it's the wrong place to start.
You have a Strat - live with it for now. When you get 'good' you'll know by then why you might need another guitar & what that guitar ought to be.
In the meantime, learn how to play what you have.
Half of any guitarist's sound is the guitarist, not the gear he uses.
So you need to learn to walk before you can run.
As for an amp - you know you can get an app for your phone for free that will be as good as anything with its own speakers that costs less than a few hundred bucks/quid/shekels. Here's one for starters - IK Multimedia's AmpliTube in its many forms.
Now, to go this route, you will need an interface, starting at around 40 bucks, but you already saved the other 40 on the mini amp & you're in no danger of irritating your neighbours.
The last thing… is that you can't properly get that 'metal' sound at low volume no matter what gear you own, because to do it 'properly' there needs to be acoustic feedback between amp & guitar. So, in the meantime, use a modelling amp that will at least go some way towards the sound.
I've done entire commercial albums using modelling amps - they do not suck.
Slammed through enough modelled valve distortion, with even a fuzz box in front, you're on your way.
Keep it up & never look back.
btw, I'm not even going to start the list of very very serious guitarists who are famous for playing Strats. That would be mean ;)
*Gear Acquisition Syndrome - everybody suffers from it at some point in their lives. There's nothing worse than a bad case of GAS.