I have been on methotrexate for 7 years with great success. It takes a few months to work so be patient, but the inflammation levels in my blood halved each month for the first few months I was on it (until I had remission induced with a dose of infliximab) and have had remission periods of up to 3 years (any flares are nipped in the bud with a single dose of infliximab)
I'm 22 now and have lead a totally normal life on it, I'm a uni student and still drink etc and my docs have said this is OK as long as my liver function remains good (has been absolutely fine for the whole 7 years, obviously if anything changed I'd curb the drinking but having said that now I'm getting older I don't drink as much anymore anyway) I used to get a lot of throat infections but they were pretty minor and lets face it is nothing compared to a Crohn's/arthritis flare up!
In terms of the whole pregnancy thing I'm on the Implanon implant, recommended because of the Crohn's as it bypasses the whole malaborption issue and is very effective as I was told that I absolutely could not risk getting pregnant and wouldn't want to at this time in life anyway but when I decide to have kids thats a bridge I'll cross when I come to it.
I know it sounds like a scary drug but it has been around for years for a reason - it can work very well! I hope you get as much success as I have had!