How to know your limit

I use to be a vodka drinker but then switched to beer nd honestly forgot how much vodka i can take. Usually if ive barely ate i can only drink around 6- 7 beers bc then ile start slurring my words but wen ive ate a normal meal i can drink 15 or more. Im pre drinking because my friends want me to go to a dog racing stadium nd i know that shits gonna bore me so im wondering if anyone has advice on how much vodka to take because i dont want to b stupidly drunk just drunk enough to enjoy something thats not enjoyable. ive also barely ate today so take with that what u can.