take the center 1 e3 e5 and if 2 Nf3 attacking your pawn then 2...e6 attacking his knight and forcing him to undevelop it.
e3, then d3?

Twice before he has answered with Ne2 then Nd2. He seems to always want to trade pieces and go for a draw. I want to attack for a win

If your opponent is a strong player, with his e3 and d3 opening he will intend to close the game by locking pawns. Once the game is closed his next plan is to exchange pieces. This is because with e3 and d3 isnt giving him space especially in the center therefore he has to exchange pieces to have some mobility. He will play an strategical approach rather than aggressively going for an attacking game. His strategy is to simplify by exchanges and grind you down in the endgame.
What to do?
Play it cool! Do not over extend your position. Just maintain a strong center and develop as fast as you can. If you are well developed and his king is still in the center attempt to open up the center by exchanging the center pawns. Once the game has opened up look for ways to get the king dancing to the middle of the board by some decoying tactics.
If the position has become blocked. Avoid exchanges to let him suffer of restricted space for his pieces. You will have more tempo to reorganize your pieces for an attack. while he is making inevetible passive moves.
If you can maintain in the opening a strong center with pawns on e5,d5 and c5 do so. These pawn barrier will give you ample space behind it to mobilise your pieces.
Show me your games so I can further advise you.

If your opponent is playing e3 and d3, he is ceding both the center and a spatial advantage. So what?
How should a center advantage or a spatial advantage be used? Often an opening line will end with comments like Black has an advantage due to his control of the d file and a Q-side pawn majority. Do you know what to do with it or even what it means? This is the question you must answer, not what is Black's best move at ply 23 in the Najdorf Posion Pawn.
BTW you really should be beating someone playing e3 & d3 as white if you are anywhere near the same strength.

The only really logical explanation for e3 and d3 is to try to confuse the opponent by taking them out of book. Otherwise, it's largely garbage.
I have played a few games where people have opened with e3 and then d3. Why? and how should combat them?
Thanks!