Mixed bag / Rebids over 1C – 1D

So here’s some quick system stuff:

1C – 1D – 1M is the starting sequence:

What should bids by responder mean now? What’s the difference between 2M, 3M and 4M? What should 1NT / 2NT mean?

So I’m of the opinion that NT should never be natural where one hand is 0-7 and the other is 16+. I don’t want the weak hand on play; however, there probably is some merit to 1C – 1D – 1S – 1NT being natural (4-7 with 1-2 spades?) since there is no other way to show this hand without being overly complex. I haven’t thought too far into it – but what about playing 1NT as forcing or semi forcing?

I think that 2M should show a simple raise – 3-5 HCP with 3 trump; 3M should show 4 trump 0-4 HCP; 4M should show 5+ trump 0-4 HCP. I would play 2NT as your 4+ trump 6-7 HCP raise (a mini jacoby with a balanced hand). I would also play jump shifts by response as 4 card support and shortness – 4-7 HCP.

So:
1♣ – 1♦ – 1M:
1NT – semi forcing?
1♠ / 2♣ / 2♦ / 2♥(over spades) – natural 5+ 5-7
2M – 3-5 with 3 trump
2NT – 5-7 with 4+ trump (balanced)
2♠ (over hearts) / 3♣ / 3♦ / 3♥ (over spades) – shortness, 4+ trump, 5-7
3M – 0-4 with 4 trump
4M – 0-4 with 5+ trump