Buying you own Alcohol for Reception

So our venue is pretty lenient on the vendors that I choose. I'm able to have any bar service company as long as they list the venue under insured. Most that I have spoken to have quoted me for their services and then require that I supply the alcohol for the event. They have given me their estimates on how much they think I should buy based off of my guest count (200) but it seems extremely low. While I know they are the professionals and this isn't their first rodeo, I am terrified that we'd run out of alcohol! My FH's family and family friends like to have a good time and the estimated 2 drinks for the first hour and 1 each hour after is definitely not right. We plan on having a 4 hour reception with three beers, house red/white, and two signature drinks. The majority of the guests are beer drinkers as we live in Texas. Can anyone give me advice on how much they've bought in the past or plan to buy in this situation? Thanks