Honestly, fighting someone bigger and stronger than you is hard. There are weight categories for a reason!
No matter what you may hear about the sport, BJJ isn't just for the little guy. I've had the pleasure of being decimated by people of the same skill level or lower that had a size and strength advantage on me. This type of training isn't only fun, it's important. Fighting stronger people forces your technique to be sharper, your speed to be greater and your resilience to be more durable.
BJJ is a great sport for many reasons, the least of which is that it gives the smaller technical person the chance to win against a brute, but the ability to problem solve and adapt in real time to survive.
So, where then does strength training fit into BJJ? It's definitely important. If you think of BJJ as a six tier pyramid, fundamental mechanics would be the foundation, followed by problem solving/BJJ theory. I'd place strength training just above endurance in the center and finally the last two would be intensity and specialist techniques at the tip of the pyramid.
What other training should you do to supplement your BJJ?
I'd recommend following a program or system designed to accompany your training and not derail it. Training when you're sore, tired and hungry sucks. Take the guess work out, get some help. There's apps and coaches out there that can help. The Juggernaut AI for BJJ for example.
I think we all want to hear people compliment our technique over 'how strong' we are but wouldn't it be nice to hear both?
Become a beast on the mats and enjoy yourselves in the process