Hi, Sameen.....previous posters have it spot on. Mix feeding which begins early on and which has this much formula in the 'mix' does not work long term, and unfortunately this is not explained to people.
50/50 breast & bottle is nowhere near enough to establish breastfeeding....I mean, it's not that it is 'not quite sufficient', it really is setting up breastfeeding to dwindle away to nothing and it's amazing you have kept up any supply at all. In fact, that's good news, as it means you still have a basis for increasing your supply.
If you want to continue breastfeeding, you need to take action immediately. You can call any of the bf helplines, and you can also google 'relactation' for a protocol on how to bring your milk supply up....this will mean feeding on both breasts as often as you possibly can, in addition to using formula. You may be able to gradually reduce the formula when your breastmilk supply increases.
Fenugreek is irrelevant, as is eating and drinking - they may have a marginal effect at best, but will have no effect at all unless you are working on bringing back supply by frequent, effective breastfeeding (usually at least 8-10 times a day, on at least both breasts each time).
If your baby refuses the breast, then you need to express.
Good luck!