There is something to be said for having a small bridal party; the biggest thing to be said is that it eliminates a LOT of organizing and detail work for you. It may eliminate the hurt feelings that can occur when you have to make choices about who will be in the party and who will not. This is a good thing. Still, there are people you might want to include in the ceremony in different ways, and there are plenty of parts they can play.
They can do readings or blessings.
They can be part of rituals like unity candles or handfastings.
They can sing or play an instrument.
They can escort either of the wedding couple to the “altar”.
They can give a toast at the end of the ceremony.
Your wedding should really be YOUR wedding, without you feeling the pressure to have 18 people standing next to you, unless that is what you want. Once you make your decision, you’ll feel relieved and THAT’S a good thing too!