Using a silicone manual breast pump (AKA the Haakaa)

So I’m a FTM and my best friend (MO2 BF both) got me a silicone breast pump to help catch my let down to help build my freezer stash. My son is almost 5 weeks and I’ve been using it since he was about 3 weeks (I EBF and I don’t have intentions of returning to work anytime soon. But we’re playing the bills by ear and could have to back to work full time by the end of next month.) It catches about 1/2 oz per feeding but sometimes catches 1-2 oz. It depends on how engorged I am and how long he nurses for. We’ve had a couple of bumps in the road. We dealt with lactose overload and I’ve finally corrected it. My question is, if the silicone pump only catches my let down which is mostly foremilk, should I be pumping after nursing him to get more hindmilk? Or do you think it’ll be ok? My best friend told me that she never separated her milk and always just fed the foremilk to her daughters. But she also believed that she only made “skim milk”. Which I think she just didn’t pump long enough to be getting the hindmilk and was only seeing foremilk. Any suggestions? TIA!