Who do i pick for biridesmaids?

It is incredibly rude to ask to be someone's bridesmaid (or even worse, assume that you will be!). I would squash that kind of behaviour asap. "We haven't decided whether or not we will have a bridal party yet, and if we do, who will be in it. If we decide to have a bridal party, we will be contacting people to invite them at that point."

As for who you pick, you need people around you on the day who will be calm and helpful, and who will focus on supporting you, not on their own dramas. Personally, I would delay making choices until a year or so before the wedding at the earliest - relationships change over time, and it is so common to hear of brides who asked people to be bridesmaids 2 or 3 years before their wedding, who then regret it when the wedding is just a few months away.

And you don't need to invite anyone so that they feel 'included'. If a person is invited to the wedding, then they are being 'included'. The only exception would be that it's unkind to invite all but one in a small group - so, for example, asking 4 out of your 5 cousins to be bridesmaids, or 3 out of your 4 friends that you always socialise with as a group would be unkind to the one person who is excluded.

" you don't want to upset anyone, but equally, you don't want to be upset"

Also worth pointing out that you are almost 100% guaranteed to upset someone with your wedding planning, so you might as well decide in advance that whoever you upset, it won't be you!