What should I do about not making up my missed fasting days from last Ramadan due to pregnancy, given that I miscarried and did not make them up, and then became pregnant again and did not pay the fidyah, and that I am weak, so should I fast or pay the fidyah?

What you have done by breaking your fast is permissible if the doctor is trustworthy. If you broke your fast out of fear for yourself, then you only owe a make-up fast. However, if the fear was for the fetus, then you owe a make-up fast along with an expiation (Kaffarah) for each day (750 grams of the local staple food for one needy person). The expiation is not waived; it remains a debt upon you.

Delaying the make-up fast of Ramadan until the next Ramadan: If the excuse of pregnancy arose before there was sufficient time for you to make up the fast, some scholars do not obligate the expiation for delay due to the absence of negligence. If you were able to make up the fast after Eid and delayed it until the next Ramadan, then you owe a ransom (fidyah) unless you were unaware of the impermissibility of the delay.

If your weakness allows you to fast at a later time, then you must make up the fast. However, if the incapacity is not expected to cease, then the make-up fast is waived for you, and you must pay an expiation for each day to a needy person.