if i understand you correctly then the problem is easily fixable, i had a similar issue before where when i trade bigger its a loser trade, but found out it was no fault of the bigger position, it was simply a bad trade, but then i get shaken and on the next trade i take a bigger position then its a profitable one, i trade systematically so i play every hand that my system gives, depends on your style but in either case you need to systematize/quantify your position size and stick to it, meaning if for example you always take 2 contracts and u want to go to 3, u need to stick to it, because if ur trading is profitable over all, changing position size constantly based on how you feel in it self can turn the whole trading from profitable to losing, it would be even better if you can do it in terms of dollars, 10k per stock for example, this way you have no attachment to the quantity of the underlying besides that u know you are trading your STANDARD position size, across the board, across all instruments, this is done correctly can lead you to greatness, of course again assuming your profitable overall in the cumulative sum of your trades