In Skyrim I felt like I spoiled the game a bit by depending on Companions too much, so I'm determined to use them minimally in Fallout 4. However, I'm not the greatest player in the world and things are getting pretty tough: I just barely was able to save Ten Pines on my own. Am I going to flounder without going into Charisma enough to get lone wanderer now?
There are plenty of different possible ways to play this game, with or without a companion.
I've never taken Lone Wanderer in all the many times I've played through this game. That being said, I usually have a companion, but they're mostly around to act as a pack mule. The companion can be useful as a bit of a tank early on, as you can send them into a group of enemies to aggro them and then try to pick them off as they fight the companion. However, this becomes less useful the further you go in the game.
If you're building your character reasonably well, not even optimally, just reasonably well, then the game should get easier as you go. If you're making it without a companion already, then you shouldn't need one at any point in the future.
What qualifies as building your character reasonably well would be a separate question, and probably too broad unless very well worded. But, in short:
Use ranged weapons. Semi-automatic are generally better. Use VATS. Sneak most of the time enemies might be nearby. Stack crits by putting points into Luck and luck perks. Use your crits wisely by taking Awareness to spot the stronger enemies. Don't use a scope (high VATS cost). Get Ballistic Weave from the Railroad. Jet will save your butt, but Psychojet is even better. Explosives do insane damage, and can easily kill enemies much stronger than you.
When playing Fallout at the very hard settings, you are adding more to the challenge and it requires you to think before acting a bit more.
In Survival mode (which I assume, you may be doing...not sure), has reduced carry weight and lots of challenges, plus the enemy does more damage. Thats not even the half of the challenges of survival.
In truth, companions are liabilities.
It is easier to depend on a companion at the lower levels to tank for you, but eventually they wont at the point you are at now and further. In addition, the range of enemies you will face will intensify...you will have tougher opponents to fight, and lots more legendary tough opponents.
1. See first to your armor and weapons At all times, continue to optimize your weapons and increase the resistance and abilities of your armor. You should always be looking to tinker and improve them. You can increase your weapons damage by 15% to 20% by tinkering to improve whenever you can. The same with your armor.
2. Run away to fight another day
This is your biggest advantage over any enemy you face. No matter how close to death a Supermutant is, it will not flee. But you, you can -almost- always flee. The enemy will be there for a period while you are away. You can heal up, approach the enemy from a different angle, even get another sneak attack in. Use the cool down period to think about attack and fighting differently. If you see a fire fight going on, and you aren't in it, wait it out. Lots of great loot afterwards to get. Yes, you don't get the XP, and its craven...but when its a tough battle, its a tough battle...let others fight it.
For instance, a radscorpion can be a very tough creature to fight. Instead of trying to tackle it head on, dash your way towards a group of supermutants (This is a great scenario near Taffington Boathouse). The supermutants will fight the radscorpion, and you just run right past them all. The loot will be good, and you might even get XP. (In essence, you've made the Super Mutants your companions in the fight without risking Dogmeat or Cait!).
Once the fight dies down, skulk back, kill the remainder and loot.
Depend on your settlements and make them stronger than you are
A good settlement has a few important things: 1. Lots of well armed settlers 2. Good to great turret defenses. 3. Capacity to heal you and store stuff.
No matter how skilled you are, you can only fire one gun at a time. A good settlement can fire 10 to 15 guns at a time. Yes, settlers go down, but every bullet they take is a bullet meant for you. So arm your settlers and give them all the spare armor you find. Even give them better weapons and armor than what you carry. Give one the Cryolator, and another the plasma weapon you can't use cause you don't have enough ammo. They can make great use of it.
If you ever need to flee, and you have no friendly group of Gunners to flee into for help...try leading the enemy into your settlement.
Soon, you will have enough caps to make one of the settlers a doctor with medical skills. Once you've reached that achievement, you've made the settlement self sustaining, and more over, life sustaining for you out in the wilds of the Commonwealth. Just make sure to constantly keep arming and improving your settlers.
Dump assault rifles, laser rifles, miniguns, gatlings, whatever on them.
Dump combat armor on them, and build defensive spots for them to use.
Make sure they have a high ground to fight from against melee enemies.
In the end...companions are truly a liability, and their role as tank is near useless compared to intellect and team of settlers at your back. If you need a mule, bring dogmeat. Or simply store caches in safe spots and quickly retrieve them to bring back to your settlers.
The best place to store a good weapon, is on a settler. Preferably one of the ones you've assigned to Scavenging or Guard post.