Short Workout questions

I began swimming again 12 months ago to get in shape and lose weight (80 lbs). I swam in HS (30 yrs ago). I am now swimming 5 -6 days a week for about 30 minutes. I am looking for some advise on a routine(s) that would get the most out of a workout of this length. I can stretch the routine to 45. I'm down 50 lbs and feeling pretty good, but need some advice on a good routine. A couple things: I have some shoulder issues but it seems to be getting stronger. I currently swim: - 10 minutes *** - 10 minutes Kick board/Freestyle mix with fins - 10 minutes ***/Back mix I am looking for some suggestions that would give me some options to get a good work squeezed into my busy day, and help me lose my last 30 Lbs. Thanks for any and all suggestions