Why won't npm install modules on my Windows machine without flagging them as global?

Question

For some reason npm will only install modules globally to my Windows machine. Whenever I try installing without the -g tag, npm will hang on the initial install loading bar for a minute or two before spitting out an error. I just ran a test and tried npm install webpack, here is the resulting error log:

0 info it worked if it ends with ok
1 verbose cli [ 'C:\\Program Files\\nodejs\\node.exe',
1 verbose cli   'C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js',
1 verbose cli   'install',
1 verbose cli   'webpack' ]
2 info using npm@3.10.8
3 info using node@v6.9.1
4 silly loadCurrentTree Starting
5 silly install loadCurrentTree
6 silly install readLocalPackageData
7 silly fetchPackageMetaData webpack
8 silly fetchNamedPackageData webpack
9 silly mapToRegistry name webpack
10 silly mapToRegistry using default registry
11 silly mapToRegistry registry http://localhost:15443/
12 silly mapToRegistry data Result {
12 silly mapToRegistry   raw: 'webpack',
12 silly mapToRegistry   scope: null,
12 silly mapToRegistry   escapedName: 'webpack',
12 silly mapToRegistry   name: 'webpack',
12 silly mapToRegistry   rawSpec: '',
12 silly mapToRegistry   spec: 'latest',
12 silly mapToRegistry   type: 'tag' }
13 silly mapToRegistry uri http://localhost:15443/webpack
14 verbose request uri http://localhost:15443/webpack
15 verbose request no auth needed
16 info attempt registry request try #1 at 3:14:31 PM
17 verbose request id 2088e718f68168b2
18 http request GET http://localhost:15443/webpack
19 info retry will retry, error on last attempt: Error: connect ECONNREFUSED 127.0.0.1:15443
20 info attempt registry request try #2 at 3:14:42 PM
21 http request GET http://localhost:15443/webpack
22 info retry will retry, error on last attempt: Error: connect ECONNREFUSED 127.0.0.1:15443
23 info attempt registry request try #3 at 3:15:43 PM
24 http request GET http://localhost:15443/webpack
25 silly fetchPackageMetaData Error: connect ECONNREFUSED 127.0.0.1:15443
25 silly fetchPackageMetaData     at Object.exports._errnoException (util.js:1026:11)
25 silly fetchPackageMetaData     at exports._exceptionWithHostPort (util.js:1049:20)
25 silly fetchPackageMetaData     at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1085:14)
25 silly fetchPackageMetaData  error for webpack { Error: connect ECONNREFUSED 127.0.0.1:15443
25 silly fetchPackageMetaData     at Object.exports._errnoException (util.js:1026:11)
25 silly fetchPackageMetaData     at exports._exceptionWithHostPort (util.js:1049:20)
25 silly fetchPackageMetaData     at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1085:14)
25 silly fetchPackageMetaData   code: 'ECONNREFUSED',
25 silly fetchPackageMetaData   errno: 'ECONNREFUSED',
25 silly fetchPackageMetaData   syscall: 'connect',
25 silly fetchPackageMetaData   address: '127.0.0.1',
25 silly fetchPackageMetaData   port: 15443 }
26 silly rollbackFailedOptional Starting
27 silly rollbackFailedOptional Finishing
28 silly runTopLevelLifecycles Finishing
29 silly install printInstalled
30 verbose stack Error: connect ECONNREFUSED 127.0.0.1:15443
30 verbose stack     at Object.exports._errnoException (util.js:1026:11)
30 verbose stack     at exports._exceptionWithHostPort (util.js:1049:20)
30 verbose stack     at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1085:14)
31 verbose cwd C:\Users\MMM\Desktop\node\npmtest
32 error Windows_NT 10.0.14393
33 error argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "install" "webpack"
34 error node v6.9.1
35 error npm  v3.10.8
36 error code ECONNREFUSED
37 error errno ECONNREFUSED
38 error syscall connect
39 error Error: connect ECONNREFUSED 127.0.0.1:15443
39 error     at Object.exports._errnoException (util.js:1026:11)
39 error     at exports._exceptionWithHostPort (util.js:1049:20)
39 error     at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1085:14)
39 error  { Error: connect ECONNREFUSED 127.0.0.1:15443
39 error     at Object.exports._errnoException (util.js:1026:11)
39 error     at exports._exceptionWithHostPort (util.js:1049:20)
39 error     at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1085:14)
39 error   code: 'ECONNREFUSED',
39 error   errno: 'ECONNREFUSED',
39 error   syscall: 'connect',
39 error   address: '127.0.0.1',
39 error   port: 15443 }
40 error If you are behind a proxy, please make sure that the
40 error 'proxy' config is set properly.  See: 'npm help config'
41 verbose exit [ 1, true ]

Here are the things I've done to try and fix it so far:

• Removing proxy by running npm config set proxy null - I use a VPN for work but it is currently disconnected, I'm using a standard Comcast home internet connection

• Made sure to run the command line with admin privileges

• Changed the npm directory to C:\Users\MMM using npm config set prefix C:\Users\MMM (it was originally set to something like C:\Users\Appdata\Roaming\npm) - npm config get prefix currently returns the updated directory, and modules installed globally are correctly installed to C:\Users\MMM\node_modules.

• Updated node and npm to the latest versions, node -v returns v6.9.1 and npm -v returns 3.10.8.

• I've tried npm install, npm install %module%, npm install %module% --save, npm install %module% --save-dev - npm install %module% -g is the only thing that works.

I'm just trying to package the PDFJS library for use on a website I'm working on - I only have very basic experience with node, npm, webpack, and the command line. Any help would be greatly appreciated. Thanks!