Rehearsal Dinner

I am starting to get worried. When we intitally booked our venue for our rehearsal dinner we thought we would have about 35 people. Our venue requires a minimum of 30 people so we thought we would be fine. We have since had several people say they can't attend or aren't bringing plus ones so now we only have 28 people. I spoke with the venue a while ago about this and they said it was totally fine. I called about a month and a half ago to make some changes to the menu, but the woman was very short with me and told me she would reach back out to me in two weeks. Our wedding rehearsal is three weeks from tomorrow and I haven't heard anything back from the venue. I wanted to make some changes because we aren't going to have as many people nor are we going to be serving alcohol anymore because most of the people don't drink that will be attending. I also want to confirm what is in the ice cream parfait because if there are strawberries in it I have to pick something else because I am allergic. I wanted to send out invites to our guests for the rehearsal but I haven't because I am worried we are going to have to change plans last minute since I haven't heard back. My fiance's sister who is also a bridesmaid thinks I should give them until next week because we will then be in the same month as our wedding. I am worried about waiting to contact them next week especially since next week.is Fourth of July. Any advice? Should I look for a backup venue just in case? We gave them a $100 deposit.