We all have TONS of activities and if you have kids they have even more than TONS of activities. How do we keep everyone's gear straight? How do we not forget our yoga mat, or swim googles, or hair ties, or baseball uniform, or shampoo, or towels, etc? Here is a plan that works. Purchase a sturdy bag for each of your activities. Write the name of the activity on the bag with a sharpie, or get each bag monogrammed. Stock the bag with everything needed for the activity. If you take a shower at your gym, keep a small toiletry bag loaded with your favorite items in the bag (don't move your shampoo, lotion, deodorant back and forth from your bathroom). Just buy a second lotion, shampoo, soap etc, you aren't spending any extra money because you are still using the same amount of product. If you and your child are packing up a baseball bag, be sure to toss in a few bandaids, sunscreen and chapstick. In my kids ski bags I put an extra pair of underwear, getting ski gear off when you have to "go" can be tricky.
Once you build your individual activity/sports bags you have to teach yourself and your child to manage them. All sports equipment, uniforms, swimsuits go through the wash and back in the bags. If it's easier for you, keep a laundry-lingerie bag in your sports bag. When it's time to wash everything, put it in the lingerie bag, run it through the wash and pop it right back into the sports bag. NOTHING GETS LOST.