Few questions about SEO - I´m doing something wrong? - Seeking help from experts

Hi all guys.
First of all than you for reading my post.
I work at a startup, we threw a huge budget in adwords during 2 years. Despite I was the sysadmin I knew a little about what SEO is and always asked my bosses to start respecting it to promote our company, fucking investors who joined us decided SEO is not productive because it takes time while paid paganda works fast. We are already 2 years and half and their paid propaganda didn´t anything. Since half year I started SEO by myself, I left the servers and started taking care of the SEO with the help of "The art of SEO (Eric Enge, Stephan Spencer, Rand Fishkin, Jessie Stricchiola)" + Google + BHW (BHW is becoming my bible).

What I do:

1) Research the best keywords
2) Use the keywords in H1, title, meta description, content, at attributes.
3) Built secondary properties (blogs) which still are not strong.
4) I buy a monthly package at thehoth (Platinum) for backlinks
5) I did some Press Releases
4) Social media, when we publish twice weekly on our main blog posts are shared in FB, Twitter, G+ and Linkedin.
5) Sometimes a video,Im going to change it to 2 videos weekly on social networks.
6) I buy some .edu and .gov links here in BHW
7) Compress images more as possible
8) We use MaxCDN
9) I try to set the keywords in the URLs

I used to buy backlinks on Fiverr, today I regret, Semrush and Moz tell me I have some toxic links there, I managed to downgrade them to few (maybe 10 toxic links).

Any recommendation about what else can I do?, there must be things you experts now that is not in the books maybe?

Thank you very much for taking the time to read my post and help me.

Kind regards.

You haven't mentioned content.....

What content is on your site? How good is it? How relevant?

What about social media traffic as well? Do you have social media presence?

I agree, check your onpage, build strong content.

Also do some of the basics:

Check competitor strong backlinks and try to acquire them if possible.
Do case studies, infographics and the likes.

SEO is some bullsh1t for losers, a waste of time, take this site for example, alexa.com/siteinfo/fitgirl-repacks.site, the owner provides something useful to his audience, never bothered with seo, no social media, the domain was hit as hell with negative seo and ddoes attacks, yet you can see ranking in alexa (site up since a year).

Also most of the content is copy/paste.

You all are right, in the content i took care of keywords, but the content itself is a shit with grammar mistakes. The service/app our startup provides is very specific, transcription services and speech recognition. I guess users who come to us are looking for that specifically... in any case, there is not reason no to try your recommendations.
Would you recommend me the most best relation quality/price content writing services?

Timatigo: I disagree with you by many reasons. First of all a product must not be useful to have success, the sale and other issues are more important than the product itself, that´s why you see so many children, and even adults, with the stupid spinner.
Second, what happens if you and me, both us, and other 100 sell a useful service/product?, 102 great companies would fight to appear in the first page of google, that´s logical I guess.

I guess the book is HQ and i even recognize Fishkin is one of the members here. But its from 2012.

IMO if you bring humongous amounts of relevancy (onnpage,offpage) and link juice (onpage,offpage) then you can get to first page of G on keywords that have some search volume. Problem is with getting #1.

(ohh not forgetting using aged domain as MS, getting links from authority domains, having safe naked url/branded/lsi anchor combo, having img links, nofollow links)

charliebrooker Im new in this forum, I can´t PM you, can you PM me first please?
I want to try your services, I saw good reviews about you.

aidenhera Wow one of the writers is here?. Since it is my main SEO source, I can´t compare it too much but it seems these guys know a lot, Ill try to get talk to here.

Does someone have more recommendations about what can I do?

You should check how is the quality of your content because it's very important for SEO

If you have a strong SEO Onpage, you will need less backlinks to rank in Google.

Have you been using the disavow tool on the toxic links?

Frank, according to Semrush, from a SEO point of view we have very few errors (I always leave few errors, since I have read a 100% healthy site may be penalized by google). But it is a fact the content is low quality, while it is good for the algorithms, it is not good for customers, we will work on it, thank you for the recomendation.

safePBN not really, I didnt disavow backlinks, I contacted the webmasters asking them to remove the links, some did,others didnt even answer, I will do it too.
Thank you,kind regards.