I'm lost

I need some advice. I am male, 45 years old, 6’1" tall and weight 189 lbs. I have always been on the skinny side, was a competitive runner in high school and continued running for fitness through college. I started weight training about 4 years ago, however at least 2 years of that time I had no idea what I was doing and wasted time doing various “programs” from various sources. When I started I had very little muscle mass and low strength. I remember struggling to squat 100 lbs, deadlift 150 and bench 100 at the beginning. My weight when I started was around 170 lbs. I believed, based on what I read, that I needed to bulk for a few months and then cut for a few months. My weight fluctuated from low 160s to around 180. My strength improved initially but then plateaued. After a year or two I tried SS NLP and saw only small gains, even while bulking. Lots of resets and more wasted time without much to show for it. I also injured my lower back Sept 2017 (badly strained or partially tore muscle in lower back while deadlifting, trying too heavy a weight with poor form, there was acute pain). Kept training as pain allowed but it took 6 plus months to recover from that.

Around fall 2018 I downloaded the bridge and began that program. I ran it once, then a second time through week 6, interrupted by Christmas trip. I started over after holidays and finished week 2. My deadlift started at 224 x 5 @ 8 in September and is now at 254, Squat 5 @ 8, 184 now 194, Bench 144 now 159, Press 104 now 109. Some progress but not much, although I liked the program. My weight has increased from around 185 in Oct to 189 today. I eat about 180 gr protein per day (use whey which makes it easier to make sure I get at least that much protein per day) and guestimate the carbs and fat. I space meals every 3 to 5 hours as recommended.

I would like to get stronger, Dead 300, squat 275, bench 224, press 134+ for working sets. Any advice on what I am doing wrong? Do I just need to be patient and big gains aren’t going to come quickly at my age? Should I start the strength template?

I would do the bridge first then do the strength template.
As far as form goes you can always drop a form check video on Facebook and we’ll gladly help you out and you can also take queues from the training vlogs on YouTube.