I'm training for a half century ride on my 50th birthday, April 24. For about two months, I had been riding up to 30 miles for my Saturday morning rides. Since then, I've been increasing my weekend ride by 10% every two weeks. This weekend was my second weekend to do 37 miles. The next two weekends will be 40.

FYI: Tuesday rides are 11-18 miles of up and down hills, Thursday rides are flat 8-11 miles and Sunday (optional) are a light, slow 5-8 miles.

Concern: During my 37 mile ride this weekend, I felt like I was in the middle of a bonk at about mile 31- 32. My weekend ride ritual, since increasing rides past 30 miles has been a half banana about 30 minutes before the ride, then a Gu at 30 minutes and every 45 minutes after that until I have only about 5- 8 miles left in the ride. This morning was 3 Gu shots. During the ride I probably drink about 40 oz of water, half of the water has a Camelbak electrolyte tablet disolved in it. I drink the water first, then switch bottles at the half way point and then drink the electrolyte tablet water during the ride home.

Questions:
1. Was that a mini bonk I experienced this weekend or when you bonk you are totally done?
2. Am I eating/replenishing energy/carbs appropriately? If not, what would you do?
3. Since I am where I am at 37 miles, I will be able to increase my distance at a slower rate when I get into April. Should I keep up the pace of 10% increase every two weeks and a. keep the distance at the last tier the same until my birthday or b. give myself a rest the week before and ride a shorter amount the week before the half century? Should I increase my distance at a slower rate until April 24th?
4. Am I over thinking this because I am already at 37 miles, eight weeks before my half century?

I just don't want to bonk that day. This is important to me. Last year, when I started riding in May, I found 2 miles difficult. Thanks in advance for your replies.