I was gonna write the same. I’ve only got a few thousand but my reach is shite. Try all the hashtag tit, interactive posts and questions, reels, showing my face on stories, key times and I’m just flopping.
Magic formula is 1 post a day, 3 stories a day, 3 reels a week. Instagram values your content based on how long someone let's it sit on their screen, so carousel posts (multiple pics) are great for that. You can go down the long caption route but I find that pisses people off so I keep mine short.
Whilst I'm not an advocate of paid followers, if you pay a service to smash 50 likes on each post, that should be enough to move your posts to the discovery page (simply because they get added so quickly, fooling the algorithm into thinking it's swift engagement). I'll be honest, I'm friends with some big names in the business (we're talking actual celebs with an excess of a million followers) and they still use this tactic. Sadly, a lot of it is about beating the system.
Best advice I can give is make sure your photos are clear and your content is sincere. If you're unsure on how to edit your pics, download Lightroom mobile and look at sites like Luxelens where you can buy pretty presets that will edit your photos for you and give you a cohesive look on insta.
Working with brands is key for engagement, but not essential. If you want to work with a brand, get on their website, contact their PR, and SET A PRICE. Budgets for micro influencers (under 10k followers) can go into the THOUSANDS per post, and as I've explained before when ranting about Jeff, they will be looking at how many people are following you compared to how many likes per post. You will get paid for having 1000 followers and 150 likes per post, but you won't for having 80k followers and 300 likes per posts. Set your rate at no less than £250 for your time, that's a low ball rate in social media terms, trust me. If a brand wants to work with you, they will pay it.
You can use apps like Tribe which advertise paid partnerships, but their rates can be awfully low (£80 a post). However, it can be a great opportunity if you're looking to dip your toe in the water.
If it makes you feel better, it's taken me 5 years to amass 9k followers, yet I get paid between £700 and £2k per post. Stay true to yourself and success will come x