^^^^ x2 on this. I can completely commiserate.
When I first started lifting I decided I was a 'hardgainer' too. I don't know quite how I came to this conclusion. At that time it was either HIT or volume training and according to all the magazines you could only follow the volume 'bodybuilder' approach if you were juicing.
I wasn't so I chose HIT. Unfortunately I nailed my flag to the wrong mast and it took me a decade to realise my mistake. I did gain, but then plateaued. It was only when I quadrupled my frequency and volume and chucked training to failure in the crapper that I started to gain again. I now realise I never was a 'hardgainer', but I can't get those wasted years back.
Now I never listen to people who say 'this is too much' or 'that will lead to overtraining' or 'you can't squat and deadlift on the same day', I just try it for myself and find out if it works for me.
So I say, increase your volume and frequency and see what happens.