Is the Medela Symphony overrated?

Hello,

I'm at my wits end. I have been exclusively pumping for 4.5 months now, my son was born early and couldn't latch over many attempts which led to a bit of a psychological aversion to continuing the attempts to latch as we were both exhausted and stressed. Over the course of my pumping journey it seems I did everything wrong - pumped only 3 times a day, didn't empty my breasts fully and when I did pump, I do so for so long my nipples grazed. In the hospital I used the Medela Symphony I was getting 50ml (just under 2oz) combined within the first 3-4 days, then I basically stopped as life was a whirl wind. After a couple days of engorgement, I started using MAM electric breast pump with no lubricant and very quickly stopped as it was agony. I then turned to the Medela Harmony manual pump which I liked, however, literally until last week I had been using it wrong (short pumps rather than long drags). The Harmony has been my main pump for months, I've also tried the Medela inBra and another in bra option but I couldn't get on with them and felt like my boobs were still full after 30 mins of pumping. I was getting at max 180ml (6oz) per day from 3-4 pumping sessions but this is only 20% of my son's daily intake. I have been desperate to increase this to at least 50% so I have been pumping like a bat out of hell and managed to get it up to +300ml (10oz) per day. I thought, "surely renting the Medela Symphony would help me get even more and have more efficient pumps!". Sadly, it's been disappointing, I get less milk than with the Harmony and it takes ages. I contacted Medela and they sent a replacement pump to make sure it wasn't an error with the initial one but it's just the same.

This is my rough production on a pumping session in the afternoon/evening:
Symphony - 30-40ml in 30 mins
Harmony - 50-60ml in 20 mins

TLDR: has anyone else found a manual pump to be more their cup of tea than a hospital grade one? I feel I'm going bananas hearing how great the Medela Symphony is when it takes double the time and I get half as much milk than my Medela Harmony. Please advise!