Welcome to Pherotalk! 
If your hair is thinning, it could be that you already have a very high Testosterone level, which could translate to a higher than normal Androstenone output. At 18, it would normally be at about its highest anyway. So this suggests to me that you should be fairly careful with the non-based products to begin with and look to social/status mixes to moderate your natural none signature and carry other attractive qualities forward.
Also, don’t worry too much about losing your hair - You would surprised at how many women of all ages go gaga for bald/neatly shaven guys! In fact, better to shave the lot now rather than try and style your hair to hide it - That shows insecurity, and possibly a self-obsessed bent, which can be amongst the most outright attraction killers there is. It also leaves you with a more masculine appearance and ages you, which does get you taken more seriously by other guys around you. Don’t end-up as the comb-over king! 
Then again, there are also so many advantages to a wipe-clean head. 
My hair started receeding at around nineteen and initially, I let it grow long for a few years to try and hide it but in time that came to look daft. Once I eventually decided to shave it, I quickly found myself more attractive and in a mood to adopt a more active/social lifestyle. The next GF I collected was an absolutely stunning eighteen year old!
As for Pheros, yes Ammo is very much in the frame here. Its a balanced mix of the three main pheros, Androstenone, Androstenol and Androsterone - which projects a sexy, social and masculine vibe that goes well in many social situations and is suitable around women your age - who tend to go for a more social based signature. You will need to test Ammo to find your effective dose.
Have a read of this - All the basics of using pheros are covered here and pay attentio to the “Sweet Spot” post:
https://pheromonetalk.com/t/how-do-i-qualify-for-a-25-gift-certificate/19934
You should also look at Instant Shine, which is happy/feelgood and socially confident, IO - which has a bright/bubbly social feel that helps promote flowing conversation and helps make it easier to approach/be more approachable and IG - Which is based on Androsterone for a light smooth/suave status feel that is very well matched to your age.
There is no difference contents-wise between the togos and the 30mls - The only thing is that the spray volume of the togo is about 80% of that from a 30ml, so you may need to adjust doses if you are using multiple sprays and switching between them.
Putatives - Yes, they can be very useful but you need to remember thay are still experimental products with no warranty which may not work as reliably between individuals. Not all of them are fully understood - particularly those associated with focus. There is nothing to stop you trying them but I would strongly suggest that a while spent with the instant/consumer products first would put you in a much better position to use/evaluate them better.