Numbers revisited

So I've actually been trying to use my number system and have decided some things are clunky. One change that was easy was a writing thing. I now do 3M4 (read 3mag4) and 5N3 (read 5neg3). That just makes things faster.

But the worst thing was actually pointed out to me by someone in my estimation IS. They said negative numbers were easy to confuse with negative orders of magnitude. I'm not sure what the best solution here is - I'm thinking the original setup is best, but ideas would be mighty useful.

Positive stuff is great:

Light year 15M9.5 m 9.5x10^15 m

I just love that. It feels great. But then we have negatives... here's the original set-up.

psi 4N1.5 Pa 1.5x10^-4 N/m^2

Now, that's a little hard to read b/c N and M don't look very different, but it's unambiguous. Here's a different idea to get rid of "neg" because it mucks things up...

psi -4M1.5 Pa

That would be great if it didn't have an issue with this next one. under my original scheme:

Electron charge -19N1.6 Pa -1.6x10^-19 N/m^2

But getting rid of "neg" leaves me kinda confused here....

Electron charge -(-19M1.6 Pa)

Yeah. Gross.

So currently the negative sign shows that the whole number is negative and the N shows that the magnitude is negative. Do people think this works well enough? Ideas for improvement?

Just a parting thought... would it be better with Pos and Neg instead of Mag and Neg? P and N are easier to see so it might be better like:
-19N1.6 and 15P9.5.