i used to work out at school doing barbell bench, but now that its summer ive joined a gym and because i dont have a spotter ive been doing db bench (which i hear is better anyway)

my question is does it take longer to see gains in strength doing db bench than bb bench?

back when i would do bb bench i would see significant strength gains every 2-3 weeks.. but ever since i been working with db it seems like my gains are coming harder/slower

when i first started this summer i was doing 55s for 5-6 reps.. after about 3 weeks i felt i was ready to go up so i was using 60s, but i was struggling for about 4-5 reps.. the lower amount of reps for 60s has got me thinking that i didnt gain as much as id like to

just wondering if this is normal or if ive plateau-ed/overtrained/etc.

this is my current chest workout (the one i did today):

2 sets db bench
2 sets db incline
2 sets db decline
2 sets machine flys

about 2 minutes between sets