I have more than 15 years of marketing experience and this includes experience in growth hacking. I look forward to the possibility of talking soon.

Frankly speaking, growth hacking is much more than offering discounts or freebies.

1. Facebook login is required, because you can straight away take them to your Facebook page and show him what you got. If he or she finds the clothes interesting, they would anyway buy. They wouldn't need a coupon or discount. If they don't like them, they don't buy even if you offer 50% discount. The philosophy of discounting is getting outdated. The in-thing is to make it relevant and offer the right price, so that he makes that decision right away. The relevance can be targeting the right audience. Don't waste money on carpet bombing. Identify your target segment and run focused campaigns by following your target clients.

Engaging your prospects is the key. If you are targeting premium clients, have a cozy blog with interesting articles, tips, HD pictures, etc.

You could go thru couple of my articles that could open up some of your thoughts in this space.

https://www.linkedin.com/pulse/paradigm-shift-sales-shivadhar-soma?trk=mp-reader-card

https://www.linkedin.com/pulse/honey-shrunk-marketing-campaigns-shivadhar-soma?trk=mp-reader-card

You're onto something applicable here as far as growth hacking goes. However you need to be more aggresive with your offerings.
For example, what you listed is more or less common practice for a lot of firms - yet doesn't make it GH nor will it actually make it a must for users to act on it.
If you however add to the offering making it 30% or 50% or FREE for an added number of invites that could be leading you towards GH.
Limit a feature that is of value and offer it for free to those who successfully get 1 or more friends to become customers. etc.

It is great model to work with. Do not jump into it suddenly. Apply it on the later stages. Marketing metrics and KPIs are measurable values used by marketing teams to demonstrate the effectiveness of campaigns across all marketing channels. Contests or reward-based campaigns naturally can go viral. This assures that you are attracting the right people, who naturally will want to spread the word about your campaign. There is no one way to go viral. For anything to go viral however, there are some common factors that contribute to that velocity. Viral advocacy has and always will be the most effective growth engine for your product, brand, or cause. Going viral requires a dynamic formula with both qualitative and quantitative aspects. When you execute the release of this sequence of events, with enough “fuel” this lift what is known as a viral loop cycle into a state of perpetual amplification.
You can read more here: https://mobilemonkey.com/blog/growth-hacking-strategies
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath