What is your insulin to carb ratio? I'm trying to figure mine out. HELP

I am 5’11’ 140 pounds and trying to figure out my ratio. I’ve been a diabetic for 3 months and am on the omnipod. I am using 15:1 but when I have more protein with dinner I seem to go kind of low after dinner and at bedtime (usually I’ll have a 70-75 reading at bedtime). Should I use less insulin when I have more protein. Also, when I use the 15:1 ratio for breakfast/lunch I hit about 150-160 1 hour later and 2 hours later I’ll be at 60-70. Any suggestions from fellow TU members? Should I use the extended bolus or is this more of a trial and error thing. My basal rate is 7 units a day as I am still producing a small amount of insulin. Thanks