Dont listen to chris, you can lose your 19 DA points along with your money with the next algorithm update by google. he just messing with you.
1. Do not get duped with cheap prices or "paid" links. if you want paid links, run a PR campaign, far far better value. do some press releases if you have news to share. "paid links" of most other kinds really will bite you at some point.
2. you are not doing "everything" in your power, not even close.
3. DIY SEO can be very time consuming and hard to do properly, that is why people like you, business owners whose time is worth more than sitting and learning all about SEO, hire people whose lives revolve around SEO.
4. per my basic and quick look up of your website:
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Your top referring "followed" baclink comes from a page with DA of 55. not so stellar.
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you have 10 total "root domains" giving you 312 backlinks. looks kind of very spammy! that is 31 links per each root domain and only 10 total referring root domains.
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per a little further digging
I notice that your anchor text profile does not seem something too healthy for SEO, very little relevance, and very irrelevant variance. You need to do some keyword research and better optimize your page titles and on-page SEO and then try to integrate those KWs in a non-spammy way into your controlled back-links (those you can edit). you further really need to invest in a way to have user or third party generated content about you and your company.
there you go, now you have a few things to get started on instead of just being upset and pondering what you have done wrong or what those other guys do. SEO is no quick fix nor easy thing to mess with and requires a lot of study time and dedication on a continuous basis.
Good luck!