Just watched bits and pieces of your stream--saw you take on a few mimics earlier, and then an etheric phantom. The main thing I would tell you is that just using the pistol/shotgun alone is generally an ineffective strategy, especially later in the game. This is the reason you're running out of ammo; your bullets are inherently weak. What you need to do is combo that with something that freezes or stuns your enemies. I noticed you don't have a stun gun in your inventory; make it a priority to find one. Not only does that mean another pool of ammo you can access, but the stun gun is very good at stunning many enemies. Enemies that are stunned take additional damage from your attacks, which is huge. In the meantime, your gloo gun will also freeze enemies, and I noticed you haven't been using it against enemies. That might be because of your ammo situation, though, hard to say. You should also be trying to sneak up on enemies whenever possible, because that also gives you a bonus to damage.
Also, scan everything with your psychoscope. The mimics in the test chamber, for example. Scanning stuff will give you access to more neuromod abilities, you'll get a general idea of which types of attacks the enemies are strong or weak to, and when you max out an enemy you'll also see a note in the research giving you more details on potential weaknesses. Additionally, there's a psychomod module you can find later on that grants a damage bonus to enemies you've marked using the psychoscope.
Besides all that, though, you're actually still pretty early in the game. It's normal to not know everything you need to do. I just saw you take on a voltaic phantom, and those are legit hard just because you have far fewer long-range weapons and getting in close to stun or attack means you take damage. Definitely try to sneak around more and not attack enemies head-on; that's the most difficult way to tackle combat and you're seeing the consequences.
Oh, also: you know that you can charge your wrench attack, right? Just hold the attack button down for a second or two before releasing. Might help with some of the mimic attacks.
Also also: if a turret shows up as broken (has the wrench icon, is sparking), you can't use it to defeat Typhon, even if you've hacked it beforehand. You'll have to fix it first.
Also also also: FIX YOUR SUIT. Uncorrupted engineering operators can fix your suit all the way to 100, and suit repair kits restore 25 to your suit's health. You take more damage if your suit's damaged, so you always want to repair your suit.
