Thoughts on scaling up

[murray t turtle]

So I recently started trading with a much larger position and am skeptical as to what might be going on causing me to take extra losses. I trade intraday and follow momentum whichever direction that might be.Im currently with TD Ameritrade and am possibly going to be moving to another broker (currently looking and comparing). Recently I've noticed more and more that if I take a position on lets say "SPY" as soon as I place my order it almost immediately starts going against me; so my question is this, is it because of my position sizing, my broker, mm, or do I just have to change strategy to trade with a much larger position?

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!00% sure that's not AMTD's fault, super/charger; even though I tried to open another account with them When I had an account with them years ago ; they always sentme a trade confirm by us mail=free/LOL
But after they sent 2 cents to my bank account as confirmation; never could get AMTD charts/account to work right to send more funds.Maybe my fault---i'm not real wise when it comes to figuring out computers/LOL
Heres another reason t trade/invest/small SCALE INS UNTIL TRADE PROVES ITSELF;
Stock Traders Almanac. JAN forcaster 88% right, but failed in 1987/2008...……………………………………………………………………………………………………………………...