Gulp's browser-sync with MAMP, images are not loaded - wordpress

Question

I'm new with gulp and I hope I explain myself clearly.
I'm using gulp's browser-sync with MAMP to create a WordPress theme. When browser-sync is executed through gulp task, my WordPress site opens under localhost:3000/mytheme but without images because images are inside localhost:8888... What I'm doing wrong?
gulpfile.js is inside my theme folder:
htdocs/wordpress/wp-content/themes/mytheme/gulpfile.js
MAMP settings,
Apache port: 8888 / Nginx port: 8888 / MySQL port: 8889
gulpfile.js
var gulp = require('gulp'),
watch = require('gulp-watch'),
postcss = require('gulp-postcss'),
autoprefixer = require('autoprefixer'),
cssvars = require('postcss-simple-vars'),
nested = require('postcss-nested'),
cssImport = require('postcss-import'),
browserSync = require('browser-sync').create();
gulp.task('style', function(){
return gulp.src('./modules/style/style.css')
.pipe(postcss([cssImport, cssvars, nested, autoprefixer]))
.pipe(gulp.dest('./'));
});
gulp.task('browser-sync', function () {
var files = [
'./*.php',
'./style.css'
];
browserSync.init(files, {
proxy: "localhost:8888/my-theme",
});
});
gulp.task('watch', function(){
watch('./modules/style/**/*.css', function(){
gulp.start('style');
});
});
gulp.task('default', ['style', 'browser-sync', 'watch'], function(){
gulp.watch('./modules/style/**//**.css', ['watch']);
});

Answer 1

Now I can run Mamp/Wordpress with Gulp and here is how I've done...
Firstly I setted up a vhost with Mamp. These tutorials explain well the steps.
http://www.dennisdeacon.com/web-design/virtual-hosts-for-mamp-based-local-web-development-on-macos-sierra/
https://www.taniarascia.com/setting-up-virtual-hosts/
After setting up a virtual host, I could access to my local site via http://localhost/your-theme/ and http://my-theme.test/.
Next, I installed npm and gulp inside a WP theme folder (Node.js is installed globally) as I mentioned in my question. But I'm not sure if it's better to install these tools inside the htdocs folder or inside a WP theme folder. I did inside a theme folder because it seems easier for me.
To run the browser-sync, I used vhost url for proxy.
After this step, I could access to my site via http://localhost:3000/ with browser-sync.
To set up a vhost, I had to prepare a new WP environment with a new database inside Mamp.
Once a site is opend via localhost:8888, I could not reopen via vhost url. The site is redirected to the localhost:8888 url.
Now I can access to my site (front page) via http://localhost:3000/, but once I go to another pages, my site is redirected to http://localhost/your-theme/another-page and not http://localhost:3000/another-page. That means I can't run browser-sync task outside the front page and I don't know what is the solution...