This is a long advice post. Please do not be offended. I know you've done this before, but I see some mistakes and this advice comes from my heart with the best of intentions. I've raised $50,000 in a Kickstarter before and have made over $100,000 a year on Steam, so I really know what I'm talking about.
I think your game is under-priced. You're giving players a lot of content. If Y Press Games was putting out a game with 8 love interests and 400k words it would be $24.99.
I think, at the very least, you should up the price to $14.99-$16.99. We've tested the $9.99 price point vs. the $19.99 price point and the $19.99 game sold more because the price indicated how much more value the player was getting. You're selling yourself short!
Anyone who is put off by a higher price will add the game to their wishlist on Steam and buy it when you put it on sale. So, you're not losing an sales by a higher price. You going to work incredibly hard on this and deserve to make a decent amount of money from game sales.
Your giving a lot of bargain perks on your Kickstarter and it's really nice of you, but not conducive to raising a lot of money for your project.
If Perk A is £1, Perk B is £2, Perk C is £4, Perk D is £6, and Perk E is £8 then the perk where you actually get the game should be £15 or higher and you should not offer a 'bare bones' option. This is fund-raising, not a chance for them to get a steal.
Re: Perk A for £1. You're charging too little for a chance to be in the credits. You and I both know what a huge pain in the butt it is to make the credits page in Ren'Py. Backers don't turn in their surveys and then get mad at you for not putting their names in anyway. £1 is too little for the privilege you're giving and the hassle you'll potentially have. It should be $5 minimum. I don't know what that is in £, but please increase it for this perk.
There was an experiment where someone sold Hershey Kisses for $.01 and Lindt Chocolate Truffles for $.16. Most people bought the truffles. Then they reduced both prices by $.01. The Hershey Kisses were free and the Truffles were $.15. Now no one bought the truffles and everyone took the free kisses. Once someone is paying for something they are more inclined to spend more for more value than if you're giving away something for free. People coming to your Kickstarter are ready and expecting to spend. $5 is not much for a name in the credits. If they'll pay 1 pound then they'll pay $5, and you need every pence because the odds are most that Kickstarters fail.
You have way too many little perks before you get the game. A Kickstarter should have around 6 perks in total. Studies show that more than 6 options overwhelms people. At most you should have 2 perks before you hit the game perk:
£3.50 - Name in credits and backer only posts
£8 - All those little perks in one bundle
£15 - All prior perks and the game. It's a £19 value because those little perks cost £8. If you raise the price like I suggested then this perk should be £20.
Beta Access to the game should be £50 at the very least. We sold beta access for $100 and had 40 backers. That's $4000! We were able to had dozens more images in the final game, more songs, more story threads. Everyone won! Beta Access is a HUGE perk. They're getting access to the game months before everyone else. It shouldn't be this cheap.
The love letters are a great idea. Backers will want to collect them all--so don't give them all in one or two perks. Have one with the game perk, one with the beta perk, and one with a higher perk. People don't like incomplete sets. It will encourage them to pledge higher tiers!
I have never seen pledges where people can control parts of the game go for so cheap. They should be over $100. These are exclusive perks that effect the game for everyone.
Last, you should offer a digital art book and the sound track if you have the rights to sell it. The next perk after the game should be the Little Rewards + Game + Art Book + Sound Track + Love Letter and this should be for £30 if the Little Rewards + Game is £15. NEXT: When you launch, offer 50 of these perks as your early bird reward and take £5-9 off. People who would only get the game perk normally will spring for more because they want to be an early bird. When you sell out the 50 perks add another 50. You lose nothing, and will gain more money for the campaign.
Around 75% to 95% of your backers are going to only get the perk with the game. That means you'll need around 600 backers to hit your goal. Very few otomes have that many backers. Most have 180-300. You need to maximize what you can get from every backer or you won't be funded.
Crowdfunding is HARD. It's SO HARD. Barely any campaigns make it to their goal, no matter how modest that goal is. You have to be very cunning. It's not because you're trying to rip people off, it's because if you don't make 100% of your goal your Kickstarter will fail and you can't make the game at all! And most Kickstarters fail! Please take some of my advice so you can not only make your goal, but hit lots of stretch goals and enrich the game even more.
And again--I'm not trying to step on your toes. I wish someone had sat down with me and given me this advice on my 2nd Kickstarter. It's so hard to succeed I needed all the help I could get.