Agree with all that Tiger said (and also had bad hypos requiring repeated ambulances with first pregnancy)
I know it's complicated to switch during pregnancy but have you considered moving hospitals? Where about are you in the country? I think advice given to you is unrealistic and unsupportive. I have 6 different basal rates and my fantastic pump DSN encouraged this after lots of basal testing- you MIGHT get a basal guideline to use that you'll need to keep increasing. I'm quite angry she said its "too messy", yeah definitely messy for her. It's the point of the pump!
I too was having 5+ hypos a day which I saw as a side effect of trying to meet targets during first preg. HbA1c in the 5s because of hypos...but I'm sure I nearly died a few times. (Seriously!) I started doing it again with second preg and my DSN asked pump consultant to see me- consultant said it was much better (in her view, not necessarily colleagues') for me to be stable rather than hypo and in target. She rightly pointed out that there is no research done on the consequences of unstable (hypo-rebound-normal-hypo) on babies or pregnant women.
On complaining to my DSN and consultant that the targets were unfair and unrealistic, the switched on consultant said she believed targets were also based on research RE Type 2s and Gestational women. I think NICE/ target makers are in a tricky position raising BG targets as obviously they are best for the baby but it's almost as bad as asking a blind person to see. Every one is individual - I'm sure some Type 1s can meet these targets but as someone who was so desperate to avoid complications in my babies (tested hourly- including the night, gave up my job when preg due to demands on testing / hypos/ bloody appointments and used CGM etc), I never met targets if I was eating carbs.
Of course you will go hypo due to increasing (not just preg). I've (unusually?!) been a bit higher at the start of pregnancies contrary to research. Each time I've known I'm preg before test come back positive due to being super, super high (33) at what I believe to be implantation. (Surge of hormones)
I defo recommend low carb if you want to meet targets. I also recommend super bolusing - I would have been in the 20s without it and eating 50ish carbs. Trouble with it, is it's unlikely your DSN would have heard of super bolusing (where you take a certain amount of hourly basal rate upfront - eg an hours worth- when eating high carbs and then stopping basal rate for the hour you gave upfront) so there are no NHS guidelines for it, even from my fab pump DSN/ dietitian.
I read 'balancing diabetes with pre existing diabetes' by an American author which was very good although, like many forums, there are A LOT of diabetics quoted in there who are able to eat whatever they like, do whatever they like and somehow have perfect results.
I have a very heathy 9 month old and a very healthy 4 year old. First preg baby was 7.11lb but I was hypo all the time, second preg I was much safer and a little higher- often being 10 or 11 maybe once daily? And baby was 10.5lb but perfect.
Good luck to you and all other mums to be out there.