how can i make sure to stay under the weight limit for my luggage?

i am going to texas for a week beginning the 1st of june, i have a packing list but i need to know what i could possibly nix if i needed to because i don’t want to check my bags, i have to keep the weight under 40 pounds combined plus i am bringing my laptop and that weighs 7.57 pounds, not to mention the weight of the bags themselves…i will be staying with my friend so i can wash my clothes, but i don’t want to wear the same things over and over again! i have a few pieces that are convertible, like i have 2 tops i can wear as tops or mini dresses with leggings, but i need to know the lightest fabrics not only to stay cool but also to pack light! is there anything heavier that i could just buy there cheap and give or throw away! oh and the scrapbook is a gift to her so i can’t take that out!

here is the list:

Underwear (4-5 pair)
Shirts (3)
Shorts (2 pair)
Socks (2 pair)
Dresses (2 (1 dressy 1 casual))
Shoes (3-4 pr chucks/sandals)
Shrugs (2)
Swimming Suit (+ cover-up)
Pajamas (1 pair/2 pieces)
Jewelry (very little)
Cash
Debit card
ID card
Notebook
Puzzle Book (& pens)
Airline tickets
Hotel Reservation
Sunglasses
Keys
Toothbrush
Travel Toothpaste
Hair Things
Scrapbook
Curling Iron
Floss
Small Shampoo & Conditioner
Small Deodorant
Small Sunblock
Lip balm (1-2)
Make-up (foundation, polish, gloss)
Pads
Hair brush
Small Moisturizer
Band-Aids
Chewing gum
Motion sickness tablets
IBU’s
Inhaler
Cell Phone (w/ charger)
Computer (w/ cords and mouse)
Digital camera (w/ cables)
MP3 Player (w/ cord & earbuds)
Extra batteries and charger
DVD’s
Memory cards
Hair Straightener