Newbie needs help with Breaststroke technique

I'm 38 years old and started swimming for fitness about 3 months ago. I learned basic breaststroke in my late 20s but haven't practiced much back then. Here is a video of my breaststroke swim. www.dropbox.com/.../breaststroke 2.MOV If I sprint, it takes me about 33 seconds for 25m and 2:27 for 100m. I can maintain 2:40 per 100m when I swim long distances like 1000m, without getting tired. I have two modest goals - Swim 25m in 25 seconds and 100m in 2min. How do I quickly reach these goals? Is my problem my poor technique or lack of strength (I'm skinny)? Thanks in advance.