How big is too big?

I'm not a purse lady. I returned the last smallish cross-body I bought because it was impossible to get a checkbook-style wallet and a small water bottle in it (11x11x2 or 3). Many cross-bodies are very narrow (obviously so they are low profile).

Recently I saw some cross-body bags that were deeper, or have been looking at satchels and totes with extra straps.

However, these tend to be considerably bigger and deeper (15 x 12x 5). I don't haul a laptop or "commute" with my entire life in my purse (although who knows in the future). On one hand, I could see the larger purse being good for stuffing a scarf in, a book or file folder for the doc. office--

Still, I'm the kind of lady that wears her purse slung across her body during and entire grocery shopping trip.

When do big purses get excessively large or get in the way?

I've tried purses of different sorts before, but always feel awkward except with cross-body-- probably because I rarely if ever use a purse-- I'm low key when going out and typically carried a laptop bag or backpack with extra room for essentials at school/work in the past. Now I am to the point that I am juggling pockets and hands with a larger "smartphone", medication bottles, wallet and checkbook, multiple sets of keys, water, ect. when I am somewhere without my handy backpack.