DXM has a half-Life of 3-4 hours, meaning after 4 hours only half of the initial dose is still active, half of that 4 hours later etc etc
In 2 weeks it will have completely eliminated with even a healthy safety margin. You are good to go, it also should not dampen your ecstasy roll. By the way even if DXM was still in your system it would not dampen your roll, it would intensify it to dangerous levels, that's what serotonin syndrome is. It would feel like a roll going harder and harder until it spins out if control and you end up in the ER in the best case
Good that you ask these questions, that's the way to take control over your own safety. Any more questions you have, don't hesitate to throw them our way. Have fun!
*edit*
By the way I remember people mentioning that when DXM is overused you might build up a tolerance that seems semi-permanent, a loss of magic which is also reported with MDMA. You might want to lessen your use if you want to avoid this. It appears that that is your plan already but just thought I'd mention it