There are so many other resources that you could use which might benefit you more. In particular, the Tofugu Resource Guide might be of interest to you. If you already own Genki I would suggest finishing that first and then see if you feel like your grammar is still lacking.
E-books are good because of the fact that you can use them on the go but I personally don’t see much point in using TF when Koichi himself admits that it isn’t currently on the same level as some of the other resources you can get nowadays. EtoEto might well be worth it when it is released and understandably the lure of a lifetime subscription being thrown with TF is nice and all but I don’t think it is a good idea to waste money paying for a lifetime subscription on something you can’t use right now.
I agree (with some of the other commenters in this thread) that it is really important not to just get caught up on relying on Wanikani alone. Some of the resources I use as a self-study learner:-
Nihongogogo - Japanese Language blog - A useful blog with a variety of phrases, vocab, and tips for your learning. I particularly like her charts that have words and phrases which I sometimes print out.
Renshuu - Similar to Anki in that it uses SRS flashcards to help you learn. I don’t really like Anki and I always forget to do Memrise.
Language Exchange - If you are looking to talk to native speakers you can try this but as with any sort of website where you are talking to strangers use with caution. (I haven’t had any bad experiences on it though but it is hard to find a learning partner that might be as motivated as you).
Japanese Pod 101 - Listening resource - The spam you will get from this site is unreal. If you do use it make sure you edit your settings to take yourself off of the mailing list. I registered for a free account and downloaded all the podcasts on my phone to listen on my way to work or while cooking and stuff. Don’t try and rely on it for any structural learning but there are very interesting cultural points.
NHK Web Easy - Since the news changes every day you pretty much always have fresh reading material from this. I look for a headline that I can understand (for the most part) and try and work out what it means. For example, this article about Mount Etna is fairly straight forward if you read the news and you can look up the words you don’t know.
I also use Genki as my main textbook which I got second hand on ebay and I also picked up a bunch of primary school level study books which have cute coloring pages and stuff to learn the names of animals and objects etc because why not. Try the Wanikanify in your browser to reinforce what you learn on here. Can’t think of anyting else!