EDIT: I can explain a few more things now:
It boiled down to the setup I had of:
Longbow with 17 DEX and Archery as a fighting style, then using Hunter's Mark and Colossus Slayer to get 3+D10+D8+D6 damage to the bosses, or using two Shortswords and doing something similar. The checks I mentioned were the concentration to keep the spell going after I took a hit.
To my mind, whilst yes I am aiming to make myself good at Combat, that doesn't seem like I'm deliberately trying to find niche rules to suit me, but just choosing things wisely (and appeared a fairly standard Ranger setup when I later checked. One of the guys and I played Warhammer Fantasy alot, so we're not unaccustomed to working out what is best to use, it's two of the other people who had the opinion I was somehow playing the system.
My suggestion to the DM was either I go for the Beast Master route and rejig a few things, as people have also pointed it is considered not as strong, but it doesn't fit the character well, or we find some reason to drop probably the HP, as at the moment with some guys being really fragile it's hard to up the difficulty in his opinion as we've nearly had people die to Goblins. I have pointed out (as other have here) that other classes will get better later, but people seem to hear none of it. I'm not particularly stung by criticism of what I am doing - I'm just trying to fit in with the team and play my role accordingly.
Also thank you to whoever added tags etc. Apologies as I am somewhat new to this site.