These things are best done at mastering houses. There you will find top quality gear designed especially for mastering. You'll also find high resolution speakers, and rooms acoustically designed for critical listening. Most importantly, you'll find highly skilled and knowledgeable specialists who do nothing but master day in and day out. They are intimately familiar with all kinds of music, and can evaluate yours from a fresh perspective and with a fresh pair of ears.
Most mastering houses are more expensive than most recording studios.
That's why low budget projects often omit advanced mastering. My advice is to at least have a mastering house listen to your album. A single hour won't cost you very much, and even if you decide not to make any changes, you'll probably learn a few things that will help you with your next project.