Really struggling with any biters [early midgame, between purple and yellow science].

Hey everyone. So, I've got maybe 150 hours in Factorio before, but I never played with biters on. So, I thought i'd give it a go now, and oh BOY they are kicking my ass - mainly on my mining outposts for copper and iron. I've tried to go out and kill all nests I can see with my tank - but now so many new ones are spawning that if I'm out killing nests, there's bound to be problems elsewhere.

I've just started the process of walling off my base with stone walls, laser turrets, and roboports stocked with spare parts + repair packs. Will this be sufficient to defend my base for the time being? I really want to enjoy the TD challenge of protecting my precious base, but at this point it feels like I've spent more time either worrying/responding to attacks than actually building any defences, let alone my yellow science production.

Any tips overall would be great. I didn't like the idea of gun turrets before because of the need for ammo and the shorter range - but the Laser turrets can often die before they kill the spitters in groups. For reference, I have 3 laser turrets for every tilechunk by the stone walls surrounding my base.

Basically - I'm shit at the biters bit of the game, please tell me how to be less shit/plan more effectively. If I have to replace my iron electronic miners one more time I'll go crazy.

Thanks all.

PS. Yes, I can just "play without biters", please don't comment this, I know it's an option, and it's not what I'm asking for.