To help out with the triangle shape you're concerned about, I would look into getting a DevaCut to get some layers in there. You may have to sacrifice a bit of length now, but those layers will look better now and as your hair continues to grow out! What were you using for co-washing? and do you know your hair properties? those will help for others to give you product recommendations. You look pretty 2ish to me, which is what my hair was like when I first started. I started out with cheaper products, then moved up to more expensive ones as needed. If you want to try co-washing again, I like the Alberto V05 conditioners (the Strawberries&Cream Moisture Milk smells divine). Dunno what Sulfate-free shampoo you use, but I really like Giovanni's Tea Tree one- it's nice and tingly! TJ makes a similar one, not as tingly, but only like $3 for a bottle! Yay Trader Joes
For a rinse out, I like L'Oreal EverSleek, it's not too heavy so it won't weigh down your looser curl pattern, though it is a bit expensive. You could also try Tresseme Naturals Nourishing Moisture. I didn't use a leave-in at first, then tried Kinky Curly Knot Today... didn't think it was worth the money, though, so now i just don't fully rinse out my regular conditioner. For times when you need a lot of protein or a lot of moisture, Sally Beauty is your best friend. Their Generic Value Products Joico K-Pak Conditioner is great for protein treatments, while GVP Matrix Biolage Conditioning Balm is a great deep treatment. Both are super cheap! There are also recipes on this site to make your own treatments, but those two purchased products were great for me this past year while I was living in a dorm and couldn't just walk down the hall to the kitchen to mix up some avocado and mayonnaise without getting some interesting looks lol. For stylers, LA Looks Sport Gel is a great, cheap gel you can get at the drugstore and it comes with a TON in each bottle. I like it because I need a lot of hold to combat frizz, but LA Looks does make other gels with lighter holds if you don't want that much crunch. From there, you can add/swap other stylers and such as needed, but that should give you some good ideas to start with! Hope that helps, lemme know if you have other questions

3Aish; mid-back when curly, waist length when straight
Shampoo - Shea Moisture
Co-wash - Alberto V05
RO/LI - TNNM, L'Oreal EverSleek
Styler: Left em all at school :"(
Gel: GF Pure Clean, LALSG