Bigger weight or more reps ?

I know there's kindov a rule on this and what you are trying to achieve, what is what on amount of weight and total reps? Like more reps with lower weights achieves what? And less reps with higher weight?

Am I making sense?

I have bumped up some of my weight lately because I feel I've gotten stale in my workout. But now I'm wondering if this is the best plan for what I want my body to look like. I don't want bulk, just a lean and toned look. So should I maybe keep my weights lower and try to do more reps?

For example, using dumbells I do chest presses on the bench with 30 lb weights. I was doing 25 lb weights but could fairly easily do 10 reps (3 sets). Now I can maybe do 8-9 reps for 3 sets (maybe less the last set). Should I even be adding weight?

I feel like I am looking bulky on my upper body, not like big muscles or anything, but kindov thick. And I don't know if it's just needing to keep losing weight or something with my weight routine. I was complaining to my hubby the other night and he was saying some of it looked like from weights, like the little muscle that pops up by your neck on the shoulder (which is weird because I don't do a ton of shoulder things...) And he thought it was cool but I hate it!!!!!

Any suggestions would be greatly appreciated!!!!! I'm still wondering if I should suck up a little cash and work with a trainer at least a few times to really personalize and update my entire workout.