Yearning for a child is no different to you already having one, the feelings would still be the same as many of us who don't have children yet.
I gave up full time work as I couldn't keep taking time off, and do emergency teaching now. The job i was in was very stressful and taxing. I did find work to be a distraction though, which helps in those difficult times.
Weight gain can happen to with the drugs.
The long down reg cycle which is a combination of the pill, nasal spray and injections I honestly struggled with. One of the drugs gave me a constant migraine for 2-3 weeks and I ended up in hospital- that is a worst case scenario.
Antagonist cycles usually go over 2-3 wk period and I have been lucky in only to have minor headaches and minimal mood swings- more impatience.
I think with all we have been through( TTC for 6 yrs.- IVF 5 yrs.) we have been lucky that I don't react too negatively towards the drugs as IVF is hard enough without getting mood swings and fighting with your partner on top of it. DH's and mine relationship has not suffered much through ivf (except maybe the bedroom) we have been mostly unscathed.
Different fertility specialists use different drugs depending on the issues with why you cannot conceive, could you keep your apt, go speak with the experts and then make up your mind? They could tell you the drugs they would be using and tell you the side effects, cost etc..you don't need the child protection form to meet with them, it's just when you start the cycle ( that's what my clinic does)
On the other hand you need to ask yourself some questions:
Are YOU going to be happy with your family of 3?
Are you going to have regrets?
Do you think your relationship will cope if you suffer mood swings with the drugs?
What could you do with the money if not spent on ivf?
Do you think emotionally you can cope- as I hear through your words you are struggling?
Are you ready to keep putting your life on hold waiting for a BFP?
Are you being fair to your child?
Some tough questions, but you need to be in the right headspace to start this journey- as it's a journey. Physically, mentally and emotionally.
All the best with what you decide x