Looking for a smart Mortgage Calculator (one that covers additional variables)

Hi guys, I know there are many basic calculators available at bank sites. I was hoping to find something a bit more complex to take in more variables.

Previously I've been relying on my mortgage broker for this, I give her different scenarios and she punches the numbers in and gives me answers within minutes on the phone - but I'm acutely aware I'm becoming a pain in her backside with all my questions so it'll be best for everyone if I can do these frequent calculations myself.

I did ask her, she was a somewhat vague in her answer but did tell me its a lenders website calculators she was using. The ones I found were too basic to be useful.

Ultimately I'll be using the services of a quality accountant, financial advisor and mortgage broker - but I want to feel I can do the math relatively accurately myself in the meantime.

Non-relevant background info (for anyone who cares):
Just sold a house, will be renting for the first time in 17 years (bit scary) due to under-employment. Got a 9 month lease, the plan is to use this time to get 3 months casual income as high as possible (to be annualised for lending requirements) then get back into home ownership - actually planning to buy 2 homes (within 12 months), a PPoR and IP, though depending on future advice this could also become 2 x IP's and we stay renting longer term. Obviously these scenarios are only possible because I have equity(cash), just don't have the income to get it all over the line at this present minute.

The plan is to keep my wife around the $20,000 income (tax free) and push my own as high as possible, but I'm always looking for alternatives such as pushing hers higher if mine doesn't reach my expectations, etc etc. Would be nice if I can regularly and accurately handle this myself.