Having difficulty scaling up

Im five years into my day trading journey, 3 years into futures, the past two years Ive only been trading NQ for 3-4 hours a trading day.

Scaled up the first year trading MNQ to get to 1 NQ by the end of the year.

My daily results vary widely, some days I capture 100+ points, some days I lose 80 points, most days I make 40-60 Points.

Im averaging a little over +30 points a day per contract over the last 400 trading days.

I have down weeks but have somehow managed to avoid a net negative month.

Im capturing around 6k NQ points a year on 700 trades, so with NQ at 20k = 30% return

I allocate 30k for the NQ contract , 1k for Day Trading Margin and 29k for Drawdown Buffer so 30k all in.

With the notional value of an NQ contract around 400k, I'm using 12x leverage with allocating 30k. Which brings my return from 30% to 400%.

Im averaging 10k+ monthly income trading 1 NQ. I'm comfortable with my current my income but its obviously stupid to stay at this level when liquidity permits trading much larger sizing.

Ive tried to size up from 1 NQ to 2 NQ the past week, but I'm struggling with the bigger numbers.

Losing 1k USD in a minute or two just seems to get to me psychologically. Something clicks in my brain and says this is unsustainable, you are going to lose everything at this rate, I end up cutting a lot of winners around break even, while still letting my losers hit my stop (the same mistake I had to overcome when starting out).

Its stupid because my longterm stock/index port will swing 5 figs daily, which doesn't bother me, probably because the losses and gains aren't realized and years of watching it has desensitized me from the number fluctuating.

I know I should probably just start with adding another MNQ on top of my 1 NQ and slowly scale up but I tried and didn't enjoy it. I wouldn't get the same fill on both contracts, it was hard to get the same exit on both contracts, MNQ tends to move slightly wider than NQ,. Commissions eat more on MNQ and I have more than enough capital to trade 2 NQ.

Its a noob question and the answer is probably just stop being a pussy, but im just wondering if any experienced traders who trade big size have any advice on how to emotionally detach themselves from the larger numbers?