Not enough information to reply. What leverage does your FX trading account have? What size of trades are you talking about? And what account type?
Let me give you a clue on regular (not micro) accounts:
0.01 lot = 1000
If you buy or sell USD with 1:100 leverage, it will take 10 usd as a margin. So, maximum you can open 3 trades x 0.01 or one 0.03 having 30 usd.
If you buy or sell EURO with 1:100 leverage, it will take 10 euro as a margin. So, max you will be able to open 2 trades x 0.01. In order to open 3 trades, you need at least 30 euro for margin.
Multiply your balance to the leverage you have and you will see what is the maximum trade size available to you.